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Honeywell 880 Weather Radio User Manual

1. 0 00 c ee eeeee 7 4 Radar Indication With Text Fault Enabled On Ground coss oriori p ERDVU EE ES Deus 7 4 Schematic Cross Section of a Thunderstorm A 6 EHSI Display Over KPHX Airport With the EGPWS Display 0000 e eee eee B 5 EGPWS Test Display 000e ee eae B 6 A28 1146 102 01 Table of Contents REV 1 TC 5 PRIMUS 9880 Digital Weather Radar System Table of Contents cont List of Tables Table Page 2 1 Dual Control Mode Truth Table 2 3 2 2 PRIMUS 880 Weather Radar Equipment List 2 4 3 1 Rainfall Rate Color Coding 3 4 3 2 Target Alert Characteristics 05 3 7 3 3 Rainfall Rate Color Coding 3 13 3 4 WC 880 Controller Target Alert Characteristics 3 17 3 5 WC 884 Controller Target Alert Characteristics 3 21 3 6 Rainfall Rate Color Coding 3 24 4 1 PRIMUS 880 Power Up Procedure 4 1 5 1 Approximate Tilt Setting for Minimal Ground Target Display 12 Inch Radiator 5 8 5 2 Approximate Tilt Setting for Minimal Ground Target Display 18 Inch Radiator 5 9 5 3 Approximate Tilt Setting for Minimal Ground Target Display 24 Inch Radiator 5 10 5 4 Pitch and Roll Trim Adjustments Criteria 5 20 5 5 Stabilization In Straight and Level Flight Check Procedure uie xcu e EE et een DN 5 21 5 6 Stabilization in Turns Check Proce
2. 7 1 Test Mode With TEXT FAULTS Enabled 7 2 Fault Code and Text Fault Relationships 7 5 8 HONEYWELL PRODUCT SUPPORT 8 1 9 ABBREVIATIONS sses 9 1 APPENDICES A FEDERAL AVIATION ADMINISTRATION FAA ADVISORY CIRCULARS A 1 P rpose 4 RR ee edes A 1 Cancellation sorana e beck eek eee be A 1 Related Reading Material A 1 Background eren rere A 2 Preca utiorns lebe bee aad eaten A Table of Contents A28 1146 102 01 TC 2 REV 1 A B Figure 2 1 2 2 3 1 4 8 A28 1146 102 01 REV 1 PRIMUS 9880 Digital Weather Radar System Table of Contents cont FEDERAL AVIATION ADMINISTRATION FAA ADVISORY CIRCULARS coNr SUBJECT THUNDERSTORMS Purpose one eisai sae ee ess Related Reading Material General sissisodan a ENIM T REN Hazards oes i DM Oo LCD i op ee ha National Severe Storms Laboratory NSSL Thunderstorm Research ENHANCED GROUND PROXIMITY WARNING SYSTEM EGPWS sseeseseseeee System Operation slllusesssss EGPWS Controls 0 00 eee Related EGPWS System Operation EGPWS Operation ssssss EGPWS Display 000 eee eens EGPWS Test 0 00 eee e eee eee List of Illustrations PRIMUS 880 Configurations Typical PRIMUS 880 Weather Radar Compon
3. TGT OR VAR ANNUNCIATOR e TGT TARGET ALERT P880 WX GREEN SELECTED MODE WX RANGE AMBER TGT DETECTED ANNUNCIATIONS Wee e VAR VARIABLE GAIN AMBER Honeywe DTRKN MAI 321 TGT FMS1 315 130 NM TEST iT 3117 t n o la TEXT AREA ANTENNA TILT Q o JE GRAY ANGLE SOR o 26 MAGENTA o a 2 odi BLUE HDG 254 GSPD 319 15 n 260 KTS YELLOW RED V e WX RANGE GREEN ANNUNCIATOR WHITE NOTES 1 IF THE BITE DETECTS A FAULT IN TEST MODE FAIL N WILL BE SHOWN N IS A FAULT CODE 2 ANY FAULT CODE CAN ALSO BE DISPLAYED IN THE MAINTENANCE MODE IN THAT CASE IT REPLACES THE ANTENNA TILT ANGLE AD 46700 R2 NOTES 1 Refer to the specific EFIS document for a detailed description 2 The example shown is for installations with TEXT FAULT disabled EFIS Test Pattern Typical 120 Scan Shown WX Figure 4 2 A28 1146 102 03 Normal Operation REV3 4 3 PRIMUS 9880 Digital Weather Radar System AD 49008 R1 WI 880 Indicator Test Pattern With TEXT FAULT Enabled Figure 4 3 Standby When Standby is selected and the radar is not in dual control mode refer to table 2 1 dual control mode truth table for dual control operation the antenna is stowed in a tilt up position and is neither scanning nor transmitting Standby should be selected when the pilot wants to keep power applied to the radar without transmitting Radar Mode Weather For purposes of weather
4. A28 1146 102 00 Radar Facts 5 27 PRIMUS 88U Digital Weather Radar system PITCH OFFSET ADJ USTMENT This in flight adjustment in made in straight and level flight when the ground returns do not follow the contours of the radar display range arcs The procedure is listed in table 5 8 D eee m ome If two controllers are installed one must be turned off If an indicator is used the procedure is the same as given below mcum Fly to an altitude of 10 000 feet AGL or greater Set range to 25 NM Adjust the tilt down until a solid band of ground returns are shown on the screen Then adjust the tilt until the T region of the ground returns start at about 20 Select RCT OFF Select STAB STB 4 times within 3 seconds The roll offset display is shown From the roll offset entry menu push the STAB STB button once more to bring up the pitch offset entry menu To change the pitch offset value pull out the GAIN knob and rotate it The offset range is from 2 0e to 42 0 0 When flying straight and level adjust so the contour of the ground returns follow the contour of the range arcs as closely as possible When change is completed push in the GAIN knob The display returns to the previous message Push the STAB STB button to go to the next menu roll gain Pitch Offset Adjustment Procedure Table 5 8 Radar Facts A28 1146 102 00 5 28 PRIMUS 88U Digital Weather Radar system ROLL GAIN ADJ US
5. PRIMUS 88U Digital Weather Radar system 3 Operating Controls WI 880 WEATHER RADAR INDICATOR OPERATION All controls used to operate the system display shown in figure 3 1 are located on the WI 880 Weather Radar Indicator front panel There are three basic controllers that are described in this section they are in order of description e WI 880 Weather Radar Indicator e WC 880 Weather Radar Controller e WC 884 Weather Radar Controller Lov EN _ GAIN R Y SBA rer F Typical PRIMUS 880 Digital Weather Radar Display Figure 3 1 The controls and display features of the WI 880 Weather Radar Indicator are indexed and identified in figure 3 2 Brightness levels for all legends and controls on the indicator are controlled by the dimming bus for the aircraft panel A28 1146 102 00 Operating Controls 3 1 PRIMUS 88U Digital Weather Radar system Honeywell oD f RANGE HA 4 rey lem 3 9 TGT SCT I 4 x E I BRT GMAP WX FP DAE wy ey OT O mn AX ACT O ACT M f we 12 AD 46693 R1 WI 880 Weather Radar Indicator Front Panel View Figure 3 2 Q Display Area See figure 3 3and the associated text which explains the alphanumeric dis play Operating Controls A28 1146 102 00 3 2 PRIMUS 88U Digital Weather Radar system ARGET T
6. PRIMUS 88U Digital Weather Radar system In prolonged turns gyro precession can occur that is tracked by the stabilization system and appears as undesirable ground targets on the indicator For example a 1eprecession error which would probably not be noticed on the gyro horizon moves the antenna beam approximately 10 500 feet ata point 100 NM from the aircraft If ground targets between 50 and 80 NM depending on aircraft altitude and the actual setting of the tilt control AD 17723 R1 Roll Stabilization Inoperative Figure 5 22 Radar Facts A28 1146 102 00 5 24 PRIMUS 88U Digital Weather Radar system ROLL STABILIZATION CHECK You can make an in flight adjustment when level flight stabilization errors are detected This procedure is done by either the WC 880 or WC 884 Weather Radar Controller or the WI 880 Weather Radar Indicator During this procedure described in table 5 7 the GAIN control acts as roll offset control After the procedure the GAIN control reverts to acting as a gain control Procedure 1 iftwo controllers are installed one must be turned off installed one must be turned off If an indicator is used as the controller the procedure is the same as given below E to an altitude of 10 000 feet above ground level s L or greater Set range to 25 NM Adjust the tilt down until a solid band of ground returns are shown on the screen Then adjust the tilt until the ing region of t
7. STORM MOTION N AD 35706 The Classic Pendant Shape Figure 5 44 A28 1146 102 00 Radar Facts 5 63 PRIMUS 88U Digital Weather Radar system AVOID STEEP RAIN GRADIENTS BY 20 MILES Figure 5 45 shows steep rain gradients Refer to the paragraph Interpreting Weather Radar Images this section for a detailed explanation of weather images GMAP WGE wy GAN j8 a C MIN S MAX AD 37251 R1 Rain Gradients Figure 5 45 AVOID ALL CRESCENT SHAPED ECHOES BY 20 MILES A crescent shaped echo shown in figure 5 46 with its tips pointing away from the aircraft indicates a storm cell that has attenuated the radar energy to the point where the entire storm cell is not displayed This is especially true if the trailing edge is very crisp and well defined with what appears to be a steep rain gradient When REACT is selected the area behind the steep rain gradient fills in with cyan Radar Facts A28 1146 102 00 5 64 PRIMUS 88U Digital Weather Radar system Crescent Shape Figure 5 46 Line Configurations AVOID THUNDERSTORM ECHOES AT THE SOUTH END OF A LINE OR AT A BREAK IN A LINE BY 20 MILES The echo atthe south end of a line of echoes is often severe and so too is the storm on the north side of a break in line Breaks frequently fill in and are particularly hazardous for this reason Breaks should be avoided unless they are 40 miles wide This is usually enough room to avoid thunderstorm hazards
8. cee eee eee ee 5 11 5 9 Earth s Curvature 0 c cece eee 5 11 5 10 Convective Thunderstorms 5 12 5 11 Unaltered Tilt 5 12 5 12 Proper Tilt Technique ssesssesse 5 13 5 13 Tilt Management With Heading Changes 5 13 5 14 Fast Developing Thunderstorm 5 14 5 15 Low Altitude Tilt Management 5 14 5 16 Antenna Size and Impact on Tilt Management 5 15 5 17 Rules of Thumb 00 cece eee eee 5 15 5 18 Manual Tilt at Low Altitudes sese 5 17 5 19 Symmetrical Ground Returns 5 22 5 20 Ground Return Indicating Misalignment Upper Right 0c ee eee eee 5 22 5 21 Ground Return Indicating Misalignment Upper Left z i reri ie atts anos 5 23 5 22 Roll Stabilization Inoperative 5 24 5 23 Roll Offset Adjustment Display Initial 5 26 5 24 Roll Offset Adjustment Display Final 5 27 5 25 Weather Radar Images sssue 5 31 5 26 Radar and Visual Cloud Mass 5 33 5 27 Squall Line 0 cece eee 5 34 5 28 REACT ON and OFF Indications 5 39 5 29 Probability of Turbulence Presence in a Weather Target ur sa Re a cides ee eee 5 41 5 30 Total Return Vector sssleesseesssss 5 44 5 31 No Turbulence seseeeseeeeeeees 5 44 Table of Contents A28 1146 102 01 TC 4 REV 1 Figure 1o og d
9. NOTE The pilotshould have freeze level information as a part of the flight planning process Radar Facts A28 1146 102 00 5 14 PRIMUS 88U Digital Weather Radar system e Theantenna size used on the aircraft alters the besttilt settings by about 1 However tilt management is the same for either size as shown in figure 5 16 10 IN ANTENNA HAS 10 BEAM 12 IN ANTENNA HAS 7 9 BEAM 18 IN ANTENNA HAS 5 6 BEAM 24 IN ANTENNA HAS 4 2 BEAM AD 46703 Antenna Size and Impact on Tilt Management Figure 5 16 NOTE A 10 inch antenna is shown for illustration purposes only e Some ofthe rules ofthumb are described below and shown in figure A 1 look down angle looks down 100 ft per mile Bottom of beam is 1 2 beam width below tilt setting A 12 inch antenna grazes the ground at 100 NM if setto 0 tilt at 40 000 ft TILT _ wo J EEAS BEAM WIDTH AD 35702 Rules of Thumb Figure 5 17 A28 1146 102 00 Radar Facts 5 15 PRIMUS 88U Digital Weather Radar system ALTITUDE COMPENSATED TILT ACT The PRIMUS 880 Digital Weather Radar has an ACT feature thatcan be selected by pulling out the tilt control knob This feature is annunciated on the radar display by adding an A suffix to the tiltreadout While in ACT or manual tilt the digital tilt readout always shows the actual true tilt of the antenna In ACT the antenna tilt is automatically adjusted with regard to the selected
10. The above two locations favor severe thunderstorm formation since these storms have less competition for low level moisture than others nearby A28 1146 102 00 Radar Facts 5 65 PRIMUS 88U Digital Weather Radar system AVOID LINE ECHO WAVE PATTERNS LEWP BY 20 MILES One portion of a line may accelerate and cause the line to assume a wave like configuration Figure 5 47 is an example of an LEWP The most severe weather is likely at S LEWPs form solid or nearly solid lines that are dangerous to aircraft operations and disruptive to normal air traffic flow 100 MILES AD 15562 R1 Line Echo Wave Pattern LEWP Figure 5 47 The S indicates the location of the greatest hazards to aviation The next greatest probability is anywhere along the advancing usually east or southeast edge of the line Radar Facts A28 1146 102 00 5 66 PRIMUS 88U Digital Weather Radar system AVOID BOW SHAPED LINE OF ECHOES BY 20 MILES Sometimes a fast moving broken to solid thunderstorm line will become bow shapedas shown in figure 5 48 Severe weather is most likely along the bulge and at the north end but severe weather can occur at any point along the line Bow shaped lines are particularly disruptive to aircraft operations because they are broken to solid and may accelerate to speeds in excess of 70 knots within an hour AD 15563 R19 Bow Shaped Line of Thunderstorms Figure 5 48 A28 1146 102 00 Radar Facts 5
11. 1146 102 00 5 40 PRIMUS 88U Digital Weather Radar system Although penetrating a storm with a red level three core appears to be an acceptable risk itis not At the lower end of the red zone there is no chance of extreme turbulence a slightchance of severe turbulence and a 4096 chance of moderate turbulence However the radar lumps allofthe rainfall rates between 12 mm to 50 mm per hour into one group a level three red Once the rainfall rate reaches the red threshold it masks any additional information about the rainfall rate until the magenta threshold is reached A red return covers a range of turbulence probabilities and the worst case must be assumed especially since extreme destructive turbulence is born in the red zone Therefore once the red threshold is reached the risk in penetration becomes totally unacceptable Likewise once the magenta threshold is reached it must be assumed that more severe weather is being masked LEVEL 1 LEVEL 2 LEVEL 3 LEVEL 4 GREEN YELLOW RED MAGENTA 100 ea ee De ee Les 90 E 80 d R 70 a Q 60 a W 50 z UJ 4096 D 30 E 2096 1096 096 4 mm Hr 12 mm Hr 50 mm Hr RAINFALL RATE AD 15357 R2 Probability of Turbulence Presence in a Weather Target Figure 5 29 A28 1146 102 00 Radar Facts 5 41 PRIMUS 88U Digital Weather Radar system Turbulence Detection Theory The PRIMUS 880 Digital Weather Radar uses a turbulence detection t
12. 1146 102 00 5 44 PRIMUS 88U Digital Weather Radar system TURBULENT AD 17727 R19 Turbulent Figure 5 32 Turbulence Detection Operation With the radar in the WX mode and with 50 miles or less range selected pushing the TRB switch turns on the turbulence detection mode Areas of detected turbulence are displayed in soft white as shown in figure 5 33 Soft white is a high contrast shade of white that has a slight gray appearance i SUPP pp a GAIN m TT o PAG gt MI S MAX AD 46707 R1 Weather Display With Turbulence Figure 5 33 If any range greater than 50 miles is selected turbulence detection turns off and remains off until 50 miles or less is reselected Similarly if any mode other than WX is selected turbulence detection turns off A28 1146 102 00 Radar Facts 5 45 PRIMUS 88U Digital Weather Radar system Mode annunciation for the turbulence detection mode is the T legend that is added to the WX annunciation The resultant annunciation is WX T for weather and turbulence The color bar legend on the dedicated radar indicator includes a T within a soft white square whenever turbulence detection is turned on EFIS MFD does nothave a color bar legend The PRIMUS 880 Digital Weather Radar measures the motion of raindrops to determine areas of turbulence The radar must detect precipitation before it can detect turbulence It cannot detect clear air turbulence WARNING THE PRIMUS
13. A low level turbulent area is the shear zone associated with the gustfront Often a roll cloud on the leading edge of a storm marks the top of the eddies in this shear and it signifies an extremely turbulent zone Gust fronts move far ahead up to 15 miles of associated precipitation The gust front causes a rapid and sometimes drastic change in surface wind ahead of an approaching storm Advisory Circular 00 50A Low Level Wind Shear explains in greater detail the hazards associated with gust fronts Figure 1 shows a schematic cross section of a thunderstorm with areas outside the cloud where turbulence may be encountered e Itis almostimpossible to hold a constant altitude in a thunderstorm and maneuvering in an attemptto do so produces greatly increased stress on the aircraft It is understandable that the speed of the aircraft determines the rate of turbulence encounters Stresses are leastif the aircraft is held in a constantattitude and allowed to ride the waves To date we have no sure way to pick soft spots in a thunderstorm A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 5 PRIMUS 88U Digital Weather Radar system ICING e Updrafts in a thunderstorm support abundant liquid water with relatively large droplet sizes and when carried above the freezing level the water becomes supercooled When temperature in the upward current cools to about 15 C much of the remaining water vapor sublimates a
14. Brightness or BRT LSS Lightning Sensor System The BRT knob is a single turn control that adjusts the brightness ofthe display Clockwise cw rotation increases display brightness and counterclockwise ccw rotation decreases brightness An optional BRT LSS four position rotary switch selects the separate LSZ 850 Lightning Sensor System LSS operating modes and the brightness control on some models Its LSS control switch positions are as follows e OFF This position removes all power from the LSS e SBY Standby This position inhibits the display of LSS data but the system accumulates data in this mode e LX Lightning Sensor System In this position the LSS is fully operational and data is being displayed on the indicator e CLR TST Clear Test In this position accumulated data is cleared from the memory of the LSS After 3 seconds the test mode is initiated in the LSS Refer to the LSZ 850 Lightning Sensor System Pilots Handbook for a detailed description of LSS operation TILT The TILT knob is a rotary control that is used to select the tilt angle of the antenna beam with relation to the horizon CW rotation tilts beam upward to 15 ccw rotation tilts beam downward to 15 A digital readout of the antenna tilt angle is displayed on the CRT with 0 5 resolution e PULL ACT Altitude Compensated Tilt Function When the TILT control knob is pulled out the system engages the ACT In ACT the antenn
15. EHSI Display Over KPHX Airport With the EGPWS Display Figure B 1 A28 1146 102 01 Enhanced Ground Proximity Warning System EGPWS REV 1 B 5 PRIMUS 9880 Digital Weather Radar System EGPWS Test When the EGPWS is selected for display it can be tested Push the remote mounted EGPWS TEST button to display the test format shown in figure B 2 EGPWS Test Display Figure B 2 Enhanced Ground Proximity Warning System EGPWS A28 1146 102 01 B 6 REV 1 PRIMUS 9880 Digital Weather Radar System Index A Abbreviations 9 1 Accelerative error 5 18 Altitude compensated tilt 5 16 C Categorizing storms 5 35 D Dynamic error 5 18 E Enhanced ground proximity warning system EGPWS B 1 annunciators B 2 FAIL B 2 INHIB B 2 ON B 2 TERR B 2 displays B 4 obstacle display color definitions B 4 EGPWS test B 6 push buttons controls B 2 INHIB button B 2 ON terrain button B 2 system operation B 1 controls B 1 EGPWS operation B 3 related EGPWS system operation B 3 A28 1146 102 01 REV 1 F Federal Aviation Administration FAA Advisory Circulars recommended radiation safety precautions for ground operation of airborne weather radar A 1 background A 2 cancellation A 1 precautions A 2 purpose A 1 related reading material A 1 thunderstorms A 4 general A 4 hazards A 4 national severe storms laboratory NSSL thunder storm research A 11 purpose A 4 related reading
16. Forced Standby Feet Ground Clutter Reduction Ground Mapping Global Positioning System hour High Voltage Power Supply Inhibit Input Output Inoperative Inch Inertial Reference System Knot s Line Echo Wave Pattern Lightning Sensor System Multifunction Display millimeter Monitor Maximum Permissible Exposure Level Navigation Navigation Display Nautical Miles National Severe Storms Laboratory National Weather Service Oscillator Plan Position Indicator Pulse Pair Processing A28 1146 102 01 REV 1 RCT REACT RCVR RTA SBY STBY SCI SCT SECT SECT SLV SPEX SRC STAB STC TCAS TERR TGT TRB TRV TST TURB UDI UNCAL VAR VIP WOW WX XMIT XMTR XSTC A28 1146 102 01 REV 1 PRIMUS 9880 Digital Weather Radar System Rain Echo Attenuation Compensation Technique Receiver Receiver Transmitter Antenna Standby Serial Control Interface Scan Sector Sector Scan Slave Spares Exchange Source Stabilization Sensitivity Timing Control Traffic Alert and Crew Alerting System Terrain Target Turbulence Total Return Vector Test Turbulence Universal Digital Interface Uncalibration Variable Variance Video Integrated Processor Weight on Wheels Weather Transmitter Extended Sensitivity Timing Control Abbreviations 9 3 9 4 blank PRIMUS 88U Digital Weather Radar system Appendix A Federal Aviation Administration FAA Advisory Circulars NOTE
17. TILT control knob is pulled out the system engages the ACT option In ACT the antenna tilt is automatically adjusted with regard to the selected range and barometric altitude The antenna tilt automatically readjusts with changes in altitude and or selected range In ACT the tilt control can fine tune the tilt setting by 2 ACT is annunciated with an A following the digital tilt legend The digital tilt readout always shows the commanded tilt of the antenna regardless of the tilt command source ACT command or manual tilt command Operating Controls A28 1146 102 03 3 22 REV 3 PRIMUS 88U Digital Weather Radar system WARNINGS 1 TO AVOID FLYING UNDER OR OVER STORMS FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH ABOVE AND BELOW YOUR FLIGHT LEVEL ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS O RANGE RANGE is a rotary control used to select one of six ranges 10 25 50 100 200 and 300 NM The seventh position ofthe range switch is flight plan mode Selecting FPLN blanks the radar information from the EF IS display and the mode annunciation flashes if a radiating mode is selected The EFIS is setto a range determined by the installation Target alert can be used in the FPLN mode With target alert on in the FPLN mode the targetalert armed annunciation green TGT is displayed The RTA becomes active and starts searching for a hazardous target from 5 to 55 miles and 37 5 dead ahead No radartargets are displayed If a haz
18. The firstis called The Great Plains Quadrant Effect that is seen most often when flying over the great plains of central United States In this region property lines fences roads houses barns and power lines tend to be laid out in a stringent north south east west orientation As a result radar returns from these cardinal points of the compass tend to be more intense than returns from other directions and the display shows these returns as bright north south east west spokes overlaying the ground map The second phenomenon is associated with radar returns from water surfaces generally called sea clutter as shown in figure 5 3 Calm water reflects very low radar returns since it directs the radar pulses onward instead of backward i e the angle of incidence from mirrored light shone on it at an angle The same is true when viewing choppy water from the upwind side The downwind side of waves however can reflecta strong signal because of the steeper wave slope A relatively bright patch of sea return therefore indicates the direction of surface winds REFLECTION gee CALM WATER OR WATER WITH CHOPPY WATER PROVIDES SWELLS DOES NOT PROVIDE GOOD RETURN FROM GOOD RETURN DOWNWIND SIDE OF WAVES WIND DIRECTION AT SURFACE OF WATER PATCH OF SEA RETURNS AD 12056 R2 Sea Returns Figure 5 3 Radar Facts A28 1146 102 00 5 4 PRIMUS 88U Digital Weather Radar system TILT MANAGEMENT The pilot can use tilt
19. When displaying checklist the TGT function is inoperative e TST Test The TST position selects the radar test mode A special test pattern is displayed to verify system operation The TEST legend is displayed in the mode field Refer to Section 4 Normal Operations for a description of the test pattern WARNING UNLESS THE SYSTEMIS IN FORCED STANDBY THE TRANSMIT TER IS ON AND RADIATING X BAND MICROWAVE ENERGY IN TEST MODE REFER TO SECTION 6 MAXIMUM PERMISSIBLE EXPOSURE LEVEL MPEL e FSBY Forced Standby FSBY is an automatic nonselectable radar mode As an installation option the indicator can be wired to the weight on wheels WOW squat switch When wired the RTA is in the FSBY mode when the aircraftis on the ground In FS BY mode the transmitter and antenna scan are both inhibited the display memory is erased and the FSBY legend is displayed in the mode field When in the FSBY mode pushing the STAB button 4 times in 3 seconds restores normal operation The FSBY mode is a safety feature that inhibits the transmitter on the ground to eliminate the X Band microwave radiation hazard Refer to Section 6 Maximum P ermissible Exposure Level MPEL WARNING FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERA TOR TO ENSURE SAFETY FOR GROUND PERSONNEL In installations with two radar controllers itis only necessary to override forced standby from one controller If either controller is returned to standby mode w
20. yellow and magenta Cyan represents the least reflective return yellow is a moderate return and magenta is a strong return If GMAP is selected before the initial RTA warmup period is complete approximately 45 to 90 seconds the white WAIT legend is displayed in the mode field In wait mode the transmitter and antenna scan are inhibited and the memory is erased When the warmup period is complete the system automatically switches to the GMAP mode e FP FlightPlan TheFP position puts the radarsystemin the flight plan mode which clears the screen of radar data so ancillary data can be displayed Examples of this data are Navigation displays Electrical discharge lightning data NOTE In the FP mode the radar RTA is put in standby the alphanumerics are changed to cyan and the FLTPLN legend is displayed in the mode field Operating Controls A28 1146 102 00 3 14 PRIMUS 88U Digital Weather Radar system The target alert mode can be used in the FP mode With target alert on and the FP mode selected the target alert armed annunciation green TGT is displayed The RTA searches for a hazardous target from 5 to 55 miles and 37 5 degrees of dead ahead No radar targets are displayed If a hazardous target is detected the target alert armed annunciation switches to the alert annunciation amber TGT This advises the pilot that a hazardous target is in his flightpath and he should select the WX mode to view it NOTE
21. 70 PRIMUS 88U Digital Weather Radar system REE Ex ZU EN CIR ZEN w BECEBEEER LINE OF REGION 195 174 151 TILT LIMITED EJE 3 e e SIGHT LIMITED REGION AD 35711 TILT Setting for Maximal Ground Target Display 18 Inch Radiator Table 5 14 NOTES 1 The line of sight distance is nominal Atmospheric conditions and terrain will offset this value 2 Tilt management for 24 inch radiator installation operates in a similar manner A28 1146 102 00 Radar Facts 5 71 5 72 blank PRIMUS 9880 Digital Weather Radar System 6 Maximum Permissible Exposure Level MPEL Heating and radiation effects of weather radar can be hazardous to life Personnel should remain at a distance greater than R from the radiating antenna in order to be outside of the envelope in which radiation exposure levels equal or exceed 10 mW cm the limit recommended in FAA Advisory Circular AC No 20 68B August 8 1980 Subject Recommended Radiation Safety Precautions for Ground Operation of Airborne Weather Radar The radius R to the maximum permissible exposure level boundary is calculated for the radar system on the basis of radiator diameter rated peak power output and duty cycle The greater of the distances calculated for either the far field or near field is based on the recommendations outlined in AC No 20 68B The advisory circular is reproduced without Appendix 1 in Appendix A of this guide The
22. Operating Controls 3 21 PRIMUS 9880 Digital Weather Radar System s TRB Turbulence Detection TRB switch is used to select the turbulence detection mode of operation The TRB mode can only be selected if the MODE switch is in the WX position and the selected range is 50 miles or less The weather turbulence mode is annunciated in the mode field with the green WX T legend Areas of at least moderate turbulence are shown in soft white CAUTION TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF RAINFALL THE PRIMUS 880 DIGITAL WEATHER RADAR SYSTEM DOES NOT DETECT CLEAR AIR TURBULENCE WARNING UNDETECTED TURBULENCE CAN EXIST WITHIN ANY STORM CELL REFER TO SECTION 5 RADAR FACTS OF THIS GUIDE FOR ADDITIONAL INFORMATION Selecting the 100 200 or 300 mile range turns off the turbulence detection The T is deleted from the mode annunciation and variable gain is engaged if previously selected Subsequent selection of ranges of 50 miles or less re engages turbulence detection A description of the turbulence detection capabilities and limitations can be found in Section 5 Radar Facts of this guide 6 TILT The TILT switch is a rotary control used to select tilt angle of antenna beam with relation to the horizon CW rotation tilts beam upward to 15 ccw rotation tilts beam downward to 15 A digital readout of the antenna tilt angle is displayed on the EFIS e PULL ACT Altitude Compensated Tilt Function When the
23. Pitch Gain NOTE NOTE Atthe time ofinstallation the programming strap STAB TRIM ENABLE determines ifthe roll and pitch gain and pitch offset adjustment features are available Consult the aircraft installation information to determine the installed configuration Forced Standby Override e Function Forced standby places the radar in a standby mode on the ground that prevents the radar from radiating and therefore exposing ground personnel to radiation exposure This mode is annunciated as FSBY STBY on EFIS in systems where mode annunciations are made e Entry Method Power up aircraft on the ground or land the aircraft with the radar powered e Exit Method Push the STAB button 4 times within 3 seconds on radar indicator or on controller Operating Controls A28 1146 102 00 3 26 PRIMUS 88U Digital Weather Radar system Roll Offset Function Roll offset permits exact compensation of the antenna roll to eliminate the effects of small errors in the aircraft radar installation Constantly lopsided ground returns can be eliminated Refer to Section 5 Radar Facts table 5 5 Entry Method Using only one controller that is in the WX and variable gain modes selectRCT OFF Push STB 4 times within 3 seconds Verify that VAR and RCT are not displayed Control The GAIN control is used to adjust the roll offset Exit Method Push STAB once to continue with the next adjustment Roll Gain Function Rollg
24. RTA CONTROLLER WC 880 a 2 fra Cle CESS SSG pl rg b p ALYY ESL PP Mer 4 Js Jo Js per JED E m OE put fy MAIN I RADAR T SiV TILT Q OIC Ie Ce ae o Or n ain RADAR SLV TuT OPTIONAL MFD AND 2ND CONTROLLER SINGLE OR DUAL EFIS eter PRIMUS 880 Configurations Figure 2 1 System Configurations A28 1146 102 00 2 2 PRIMUS 88U Digital Weather Radar system The third system configuration is similar to the second except that a Honeywell multifunction display MFD system is added As before single or dual controllers can be used When a single controller is used all displays show the same radar data Dual controllers are used to operate in the dual mode The MFD can be slaved to either controller to duplicate the data displayed on the selected side Table 2 lis a truth table for dual control modes Left Right Controller Controller Left Side Right Side RTA Mode NOTE 1 NOTE 1 Mode OFF Standby SLV Standby Standby Standby Standby Standby SLV Standby Standby Lo ow fmon ww ore ow smon MERE E A 308 4 Hal Owes Oey ON Standby ON 2 Standby 2 ow ow ow ow Standby Standby Standby Standby Standby Dual Control Mode Truth Table Table 2 1 A28 1146 102 00 System Configurations 2 3 PRIMUS 9880 Digital Weathe
25. Upon exiting stabilization may be either OFF or ON depending on how many times it was pushed during the procedure Be sure to set stabilization OFF or ON as desired 3 Ifuponentering the adjustment mode no changes are desired keep the gain knob pushed in and repeatedly push STAB until the mode is exited Operating Controls A28 1146 102 00 3 28 PRIMUS 9880 Digital Weather Radar System 4 Normal Operation PRELIMINARY CONTROL SETTINGS Table 4 1 gives the proper power up procedure for the PRIMUS 880 Digital Weather Radar System Verify that the system controls are in the positions described below before powering up the radar system Mode control Off GAIN control Preset Position TILT control 15 Take the following precautions if the radar system will be operated in any mode other than standby or forced standby while the aircraft is on the ground e Direct nose of aircraft so that antenna scan sector is free of large metallic objects such as hangars or other aircraft for a minimum distance of 100 feet 30 meters and tilt the antenna fully upwards Do not operate the radar system during aircraft refueling or during refueling operations within 100 feet 30 meters Do not operate the radar if personnel are standing too close to the 120 forward sector of aircraft Refer to Section 6 Maximum Permissible Exposure Level in this guide Operating personnel should be familiar with FAA AC 20 68B which is reprodu
26. adjust mode and to override forced standby NOTE Some controllers annunciate OFF when stabilization is OFF 6 TRB Turbulence Detection TRB is a switch used to select the turbulence detection mode of operation The TRB mode can only be selected if the FUNCTION switch is in the WX or RCT positions and the selected range is 50 miles or less The weather turbulence mode is annunciated in the mode field with the WX T legend Areas of atleast moderate turbulence are shown in soft white The turbulence threshold is five meters per second A28 1146 102 00 Operating Controls 3 17 PRIMUS 9880 Digital Weather Radar System WARNINGS 1 TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF RAINFALL THE PRIMUS 880 DIGITAL WEATHER RADAR SYSTEM CANNOT DETECT CLEAR AIR TURBULENCE 2 UNDETECTED TURBULENCE CAN EXIST WITHIN ANY STORM CELL REFER TO SECTION 5 RADAR FACTS OF THIS GUIDE FOR ADDITIONAL INFORMATION Selecting the 100 200 or 300 mile range turns off the turbulence detection The T is deleted from the mode annunciation and variable gain is engaged if previously selected Subsequent selection of ranges of 50 miles or less re engages turbulence detection A description of the turbulence detection capabilities and limitations of this radar system is given in Section 5 Radar Facts of this guide 7 RANGE The RANGE switches are two momentary contact buttons that are used to select the operating range of the radar and LSS if i
27. adjustment 4 Roll gain adjustment 004 Pitch gain adjustment Interpreting Weather Radar Images Weather Display Calibration Variable Gain Control aasa A28 1146 102 00 TT 2 1 pus 3 1 modd 3 1 11 20 TT 3 26 ee 3 26 TEF 3 27 3 27 T 3 27 3 28 O0 rmpDm e WWWWNNNNKPEHEHEYYT GF AARAA gt br dae dae i ler EE S os fc IOP OuQoU ni 0o00Urn e Table of Contents TC 1 PRIMUS 9880 Digital Weather Radar System Table of Contents cont Section Page 5 RADAR FACTS cont Rain Echo Attenuation Compensation Technique REACT iiec seb eR RR EU ME at eas 5 97 Shadowing sseselseseeeere 5 40 Turbulence Probability Lss 5 40 Turbulence Detection Theory 5 42 Turbulence Detection Operation 5 45 Hail Size Probability 5 47 Spotting Halll zz he pated demented wate 5 48 Azimuth Resolution 0 e eee eee 5 53 Hadome asses ued teeth EE Lite es 5 54 Weather Avoidance 0 0 cece e eee 5 55 Configurations of Individual Echoes Northern Hemisphere eee eee 5 60 Line Configurations 0005 5 65 Additional Hazards suus 5 68 Ground Mapping 0 ce eee eee 5 69 6 MAXIMUM PERMISSIBLE EXPOSURE LEVEL MPEL 2 n seen gg ae nes eee 6 1 7 IN FLIGHT TROUBLESHOOTING
28. also active and the azimuth lines can be displayed or removed The other radar controls do not change the terrain display but if they are used while the EGPWS is displayed they control the radar receiver transmitter antenna RTA and the effect is displayed when the system returns to the radar display EGPWS Controls The typical EGPWS installation has remotely mounted push button controls and status annunciators that are related to the display on the radar indicator The paragraphs below give a functional description of the recommended controls A28 1146 102 03 Enhanced Ground Proximity Warning System EGPWS REV 3 B 1 Use or disclosure of the information on this page is subject to the restrictions on the title page of this document PRIMUS 9880 Digital Weather Radar System PUSH BUTTON CONTROLS The following remotely mounted push buttons control the EGPWS display e INHIB Inhibit Button When active the push on push off INHIB button prevents terrain data from being displayed on the radar indicator When the button is active the INHIB annunciator lights e ON Terrain Button When active the push on push off ON button displays terrain on the radar indicator ANNUNCIATORS The following annunciators are displayed on the radar indicator to indicate EGPWS operation e FAIL The FAIL annunciator indicates that the EGPWS has failed e INHIB The INHIB annunciator indicates that the INHIB push button has been push
29. below the flight level to avoid flying under or over storms as shown in figure 5 18 Manual tilt should also be used exclusively when analyzing weather NOTE The radar system does not have enough information to be able to tilt the beam into the wet lower portions of cells by itself The operator mustmanage tilt dynamically or manually to locate and analyze weather ACT simply adjusts the beam to the earth s surface at the selected maximum range Also itassumes that the surface is at 2000 feet above sea level Radar Facts A28 1146 102 00 5 16 PRIMUS 88U Digital Weather Radar system NM 100 AD 357039 Manual Tilt at Low Altitudes Figure 5 18 A28 1146 102 00 Radar Facts 5 17 PRIMUS 88U Digital Weather Radar system STABILIZATION The purpose of the stabilization system is to hold the elevation of the antenna beam relative to the earth s surface constant at all azimuths regardless of aircraft bank and pitch maneuvers The stabilization System uses the aircraft attitude source as a reference Several sources of error exist in any stabilization system Dynamic Error Dynamic error is the basis of the stabilization system Stabilization is a corrective process It logically follows that there must first be some error to correct In stabilization this error is called dynamic An example of dynamic error occurs when a gustlifts the rightwing and the pilot instinctively raises the right aileron and lowers the left In
30. function 3 9 Index Index 6 A28 1146 102 01 REV 1
31. inside a thunderstorm e Doavoid by atleast20 miles any thunderstorm identified as severe or giving an intense radar echo This is especially true under the anvil of a large cumulonimbus e Docircumnavigate the entire area if the area has 6 1 thunderstorm Coverage e Do remember that vivid and frequent lightning indicates the probability of a severe thunderstorm e Do regard as extremely hazardous any thunderstorm with tops 35 000 feet or higher whether the top is visually sighted or determined by radar A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 9 PRIMUS 88U Digital Weather Radar system If you cannot avoid penetrating a thunderstorm the following are some do s BEFORE entering the storm e Tighten your safety belt put on your shoulder harness if you have one and secure all loose objects e Plan and hold your course to take you through the storm in a minimum time e Toavoidthe mostcriticalicing establish a penetration altitude below the freezing level or above the level of 15 C e Verify that pitot heatis on and turn on carburetor heat or jet engine anti ice Icing can be rapid at any altitude and cause almost instantaneous power failure and or loss of airspeed indication e Establish power settings for turbulence penetration airspeed recommended in your aircraft manual e Turn up cockpit lights to highest intensity to lessen temporary blindness from lightning e f using a
32. management techniques to minimize ground clutter when viewing weather targets Assume the aircraft is flying over relatively smooth terrain which is equivalentto sea level in altitude The pilot must make adjustments for the effects of mountainous terrain The figures below help to visualize the relationship between tilt angle flight altitude and selected range Figures 5 4 and 5 5 show the distance above and below aircraft altitude that is illuminated by the flat plate radiator during level flight with 0 tilt Figures 5 6 and 5 7 show a representative low altitude situation with the antenna adjusted for 2 8 up tilt 80000 w 70 000 Z 60000L ZERO TILT 41 800 FT z 20 000 FT Z 20 000 10 500 FT E mmeh en p 77 CENTER OF RADAR BEAM 30000 10500 FT jo Qoo FT EY iu 20 000 41 800 FT 10 000 rfr 0 HH I 0 25 50 f Gna RANGE NAUTICAL MILES AD 35693 Radar Beam Illumination High Altitude 12 Inch Radiator Figure 5 4 80 000 70 000 z n 230000 14800 FT O aem k ee CENTER OF RADAR BEAM z 14 800 FT 5 RN t 29 000 FT d 20 000 gus FT am dod dits itn 0 25 50 100 RANGE NAUTICAL MILES AD 17717 R1 Radar Beam Illumination High Altitude 18 Inch Radiator Figure 5 5 A28 1146 102 00 Radar Facts 5 5 PRIMUS 88U Digital Weather Radar system 40 000 ANTENNA ADJ USTED m 30 000 FOR 2 8 UPTILT rs 20 900 FT N oe oot 5 20 000 _ CENTER E LA
33. material A 4 H Hidden modes 3 26 forced standby entry method 3 27 exit method 3 27 function 3 26 roll offset 3 26 3 27 3 28 entry method 3 27 exit method 3 27 function 3 27 use 3 27 Honeywell product support 8 1 24 hour exchange rental support centers 8 2 customer support centers 8 2 North America 8 2 Rest of the world 8 3 publication ordering information 8 4 Index Index 1 PRIMUS 9880 Digital Weather Radar System Index cont In flight troubleshooting fault access fault data fields 7 3 pilot messages 7 5 test mode with TEXT FAULTS enabled 7 2 text faults 7 5 Interpreting weather radar images 5 81 N National severe storms laboratory NSSL thunderstorm research A 11 extrapolation to different climbs A 14 hail in thunderstorms A 13 maximum storm tops A 13 modification of criteria when Severe storms and rapid development are evident A 13 relationship between turbulence and altitude A 11 relationship between turbulence and reflectivity A 11 turbulence above storm tops A 12 turbulence and echo intensity on NWS radar WSR 57 A 11 turbulence below cloud base A 12 turbulence in relation to distance from the storm edge A 12 turbulence in relation to distance from storm core A 11 use of airborne radar A 14 visual appearance of storm and associated turbulence with them A 13 Normal operation preliminary control settings 4 1 Index Index 2
34. ood AON G1 1 OT G1 G1 G1 OT G1 G1 ON G1 G1 OO aac ABRRBRRBRBBRBBBROGCC CO WOW a XQ Oo 4001 CI O00 10Oo O0 P D 7 2 A 1 B 1 B 2 PRIMUS 9880 Digital Weather Radar System Table of Contents cont List of Illustrations cont Page Turb lent ss eoesos usu cse Sets OPERE er eni dies 5 45 Weather Display With Turbulence 5 45 Turbulence Levels From Airman s Information Manual 4 220 regrupare grar eO E Dues 5 47 Hail Size Probability 00005 5 48 Rain Coming From Unseen Dry Hail 5 49 Familiar Hailstorm Patterns 5 50 Overshooting a Storm ssuuuuuusss 5 51 Short and Long Blind Alley 5 52 Azimuth Resolution in Weather Modes 5 53 Weather Display ssseeeseeeeeeee 5 55 Typical Hook Pattern sllusseesssee 5 61 V Notch Echo Pendant Shape 5 62 The Classic Pendant Shape 5 63 Rain Gradients 000 e cece eee 5 64 Crescent Shape ccc eee eee eee 5 65 Line Echo Wave Pattern LEWP 5 66 Bow Shaped Line of Thunderstorms 5 67 Ground Mapping Display 4 5 69 MPEL Boundary 0 00 cece eee eee 6 1 Fault Annunciation on Weather Indicator With TEXT FAULT Fields 00 cece eee eee eee 7 3 Fault Code on EFIS Weather Display With TEXT FAULTS Disabled
35. other words the first pulse TRV of range bin 34 is compared to the TRV for pulse two in range bin 34 A totalreturn vector is shown in figure 5 30 In the simplified example of figure 5 30 the range bin contains five raindrops of equal size that are at slightly different ranges The amplitudes ofthe returns fromthe raindrops vector length are identical because all the drops are equal in size butthe phase vector rotation ofthe individual returns varies because of the variation in the range of the raindrops The radar does not see the individual returns rather it sees the total return vector which is the vector sum of the returns from all the individual raindrops In reality the range bin could contain thousands and thousands ofraindrops which means thata longer chain of vectors are summed butthe resultis still one total return vector Radar Facts A28 1146 102 00 5 42 PRIMUS 88U Digital Weather Radar system With the very short time between radar pulses when in the turbulence mode one pulse every 0008 second little or no turbulence results in litle or no change in the size or position of the raindrops This results in little or no change in the individual returns from each raindrop and a commensurate little or no change in the total return vector Therefore when there is little or no difference between two subsequenttotalreturn vectors in the same range bin there is little or no turbulence in that range bin This is illustrate
36. out of control Occupants may feel a slight strain against seat belts or shoulder straps Unsecured objects may be displaced Slightly Occupants feel definite strains against seat belts or shoulder straps Unsecured objects are dislodged Occupants are forced violently against seat belts or shoulder straps Unsecured objects are tossed about Turbulence Levels From Airman s Information Manual Figure 5 34 Hail Size Probability Whenever the radar shows a red or magenta target the entire storm cell should be considered extremely hazardous and must not be penetrated Further support for this statement comes from the hail probability graph shown in figure 5 35 The probability of destructive hail starts ata rainfall rate just above the red level three threshold Like precipitation the red and magenta returns should be considered as a mask over more severe hail probabilities By now it should be clear that the only safe way to operate in areas of thunderstorm activity is to AVOID ALL CELLS THAT HAVE RED OR MAGENTA RETURNS Radar Facts 5 47 A28 1146 102 00 PRIMUS 88U Digital Weather Radar system 100 80 a e E RELATIVE FREQUENCY A e x T 3 4 AND LAGER HAIL LEVEL 2 LEVEL 3 LEVEL 4 YELLOW RED MAGENTA 0 AD 15358 R1 Hail Size Probability Figure 5 35 S potting Hail As previously stated dry hail is a poor reflector and therefore generates deceptively weak or ab
37. power up procedure 4 1 radar mode ground mapping 4 6 radar mode weather 4 4 standby 4 4 test mode 4 6 color bands 4 7 dedicated radar indicator 4 7 fault code 4 7 EFIS MFD ND 4 7 noise band 4 6 target alert block 4 6 text fault 4 6 O Operating controls hidden modes 3 26 roll offset 3 26 3 27 3 28 WC 884 Weather radar controller operation 3 20 BRT brightness 3 20 controller target alert characteristics 3 21 gain 3 25 mode 3 23 range 3 23 RCT rain echo attenuation compensation technique 3 21 SLV slave 3 23 STAB stabilization 3 21 TGT target alert 3 20 TILT 3 22 TRB turbulence detection 3 21 Weather radar controller operation 3 11 controller target alert characteristics 3 17 gain 3 18 LSS lightning sensor system option 3 19 radar 3 13 A28 1146 102 01 REV 1 PRIMUS 9880 Digital Weather Radar System Index cont range 3 18 SECT scan sector 3 16 SLV slave 3 19 STB stabilization 3 17 TGT target 3 16 Tilt 3 16 TRB turbulence detection 3 17 WI 880 Weather radar indicator operation 3 1 AZ azimuth 3 8 BRT brightness or BRT LSS lightning sensor system 3 9 display area 3 2 function switch 3 3 gain 3 10 range 3 8 RCT rain echo attenuation compensation technique 3 7 SCT scan sector 3 8 STAB stabilization 3 7 target alert characteristics 3 7 TGT target 3 6 tilt 3 9 TRB
38. re enter TEST mode In Flight Troubleshooting A28 1146 102 00 7 2 PRIMUS 88U Digital Weather Radar system Table 7 1 describes the six fault data fields that are displayed in figure 7 1 Fane J oen 4 mme 7700 NOTES 1 If airborne only fault fields 1 2 and 3 are displayed 2 Airborne only the current faults are displayed 3 Strap codes indicate the installation configuration that was done atthe time of installation Refer to the System Description and Installation manual for further explanation Fault Data Fields Table 7 1 The last32 faults from the last 10 power on cycles are cycled every two antenna sweeps approximately 8 seconds eon FAULT Em pilot 00 DISPLAY MESSAGE MESSAGE DIVIDER FIELD FAULT CODE LINE POWER ON gt MAINTENANCE COUNT a SN MESSAGE TRANSMIT X gt FAULT ON OFF NAME RCT T STRAP 40 CODE 1 j2 3 J4 20 WEATHER INDICATOR AD 46709 z Fault Annunciation on Weather Indicator With TEXT FAULT Fields Figure 7 1 A28 1146 102 00 In Flight Troubleshooting 7 3 PRIMUS 88U Digital Weather Kadar system Figure 7 2 shows the fault codes displayed on EFIS with text faults disabled Honeywell f f DTRK 315 AD 35708 R19 Fault Code on EFIS Weather Display With TEXT FAULTS Disabled Figure 7 2 qd GAIN 6 MAX AD 5024 Radar Indication With Text Fault Enabl
39. weak targets or it can be reduced below the calibrated level to eliminate weak returns WARNING HAZARDOUS TARGETS MAY BE ELIMINATED FROM THE DIS PLAY WITH LOW SETTINGS OF VARIABLE GAIN In the GMAP mode variable gain is used to reduce the level of the typically very strong returns from ground targets Minimum gain is with the control atits full ccw position G ain increases as the control is rotated cw from full ccw At full cw position the gain is at maximum In variable gain the color bar legend contains the variable gain VAR annunciation Selecting RCT or TGT forces the system into calibrated gain Operating Controls A28 1146 102 00 3 10 PRIMUS 88U Digital Weather Radar system WC 880 WEATHER RADAR CONTROLLER OPERATION The controls and display features of the WC 880 Weather Radar Controller are indexed and identified in figure 3 4 Brightness levels for all legend and controls on the indicator are controlled by the dimming bus for the aircraft panel OrF CC eee wx rRCT PULL hy VAR SBY GMAP ACT A PULL TILT Honeywell AD 46696 R1 WC 880 Weather Radar Controller Configurations Figure 3 4 cont A28 1146 102 00 Operating Controls 11 PRIMUS 88U Digital Weather Radar system SN Calm RCT fn Y Se PULL Y OFF CLR ACT TST f TILT Honeywell AD 46697 R19 WC 88
40. yellow TGT warning condition See the target alert characteristics in table 3 2 for a target description These annunciations advise the pilot of potentially hazardous targets directly in front of the aircraft that are outside the selected range When a yellow warning is received the pilot should select longer ranges to view the questionable target Note that target alert is inactive within the selected range Selecting target alertforces the system to preset gain Target alert can be selected only in the WX or FP modes NOTE In order to activate the target alert warning the target must have the depth and range characteristics described in table 3 2 Operating Controls A28 1146 102 00 3 6 PRIMUS 88U Digital Weather Radar system Selected Range Minimum Target Target Range NM Depth NM NM 5 5 5 55 10 10 60 25 25 75 50 50 100 100 100 150 200 200 250 300 N A FP Flight Plan 5 55 Target Alert Characteristics Table 3 2 RCT Rain Echo Attenuation Compensation Technique REACT The RCT switch is an alternate action switch that enables and disables REACT The REACT circuitry compensates for attenuation of the radar signal as it passes through rainfall The cyan field indicates areas where further compensation is not possible Any target detected within the cyan field cannot be calibrated and should be considered dangerous All targets in the cyan field are displayed as fourth level precipita
41. 0 Weather Radar Controller Configurations Figure 3 4 NOTES 1 With a controller without built in range control range is controlled from the installed EFIS navigation display 2 Controllers are available with and without the LSS function 3 Whenever single or dual radar controllers are used the radar data is displayed on the EFIS and or an MFD or navigation display ND Operating Controls A28 1146 102 00 3 12 PRIMUS 88U Digital Weather Radar system 2 RADAR This rotary switch is used to select one of the following functions e OFF This position turns the radar system off e SBY Standby This position places the radar system in standby a ready state with the antenna scan stopped the transmitter inhibited and the display memory erased STBY is displayed on the EFIS MFD e WX Weather This position selects the weather detection mode The system is fully operational and all internal parameters are set for enroute weather detection If WX is selected before the initial RTA warmup period is complete approximately 45 to 90 seconds the WAIT legend is displayed on the EFIS MFD In WAIT mode the transmitter and antenna scan are inhibited and the display memory is erased When the warmup is complete the system automatically switches to the WX mode The system in preset gain is calibrated as described in table 3 3 Rainfall Rate Color Rainfall Rate Color Coding Table 3 3 e RCT Rain Echo Attenuati
42. 1 below cloud base A 12 in relation to distance from the storm edge A 12 visual appearance A 13 Tilt management 5 5 V Variable gain control 5 37 Ww WC 884 Weather radar controller operation 3 20 mode 3 23 FSBY 3 25 GMAP 3 24 OFF 3 23 Rainfall rate color coding 3 24 STBY 3 23 WX 3 24 tilt 3 22 PULL ACT altitude compensated tilt function 3 22 Weather avoidance 5 55 Weather display calibration 5 35 Weather radar controller operation 3 11 LSS lightning sensor system option 3 19 CLR TST 3 19 LX 3 19 Off 3 19 SBY 3 19 radar 3 13 FP flight plan 3 14 FSBY forced standby 3 15 GMAP ground mapping 3 14 Index Index 5 PRIMUS 9880 Digital Weather Radar System Index cont Weather radar controller operation cont OFF 3 13 Rainfall rate color coding 3 13 RCT rain Echo attenuation compensation technique 3 13 SBY standby 3 13 TST test 3 15 WX weather 3 13 tilt 3 16 PULL ACT altitude compensated tilt function 3 16 WI 880 Weather radar indicator operation 3 1 BRT brightness or BRT LSS lightning sensor system 3 9 CLR TST clear test 3 9 LX lightning sensor system 3 9 OFF 3 9 SBY standby 3 9 function switch 3 3 FP flight plan 3 5 FSBY forced standby 3 5 GMAP ground mapping 3 4 OFF 3 3 rainfall rate color coding 3 4 SBY standby 3 3 TST test 3 5 WX weather 3 3 tilt 3 9 PULL ACT altitude compensated tilt
43. 39 Radar Facts A28 1146 102 00 5 52 PRIMUS 88U Digital Weather Radar system Azimuth Resolution When two targets such as storms are closely adjacent at the same range the radar displays them as a single target as shown in figure 5 38 However as the aircraft approaches the targets they appear to separate In the illustration the airplane is far away from the targets at position A Atthis distance the beam width is spreading As the beam scans across the two targets there is no pointat which beam energy is not reflected either by one target or the other because the space between the targets is not wide enough to pass the beam width In target position B the aircraft is closer to the same two targets the beam width is narrower and the targets separate on the display INDICATOR DISPLAY A ER AS 3 N 35 30 B 10 INDICATOR DISPLAY B AD 35705 Azimuth Resolution in Weather Modes Figure 5 40 A28 1146 102 00 Radar Facts 5 53 PRIMUS 88U Digital Weather Radar system RADOME Ice or water on the radome does not generally cause radar failure but it hampers operation The radome is constructed of materials that pass the radar energy with little attenuation Ice or water increases the attenuation making the radar appear to have less sensitivity Ice can cause refractive distortion a condition characterized by loss of image definition If the ice should cause reverberant echoes within the radome the condit
44. 67 PRIMUS 88U Digital Weather Radar system Additional Hazards TURBULENCE VERSUS DISTANCE FROM STORM CORE The stronger the return the further the turbulence will be encountered from the storm core atany altitude Severe turbulence is often found in the tenuous anvil cloud 15 to 20 miles downwind from a severe storm core Moreover the storm cloudis only the visible portion of a turbulent system whose up and down drafts often extend outside of the storm proper TURBULENCE VERSUS DISTANCE FROM STORM EDGE Severe clear airturbulence can occur near a storm mostoften on the downwind side Tornadoes are located in a variety of positions with respect to associated echoes but many of the most intense and enduring occuron the up relative windside The air rising in a tornado can contribute to a downwind area of strong echoes while the tornado itself may or may not return an echo Echo hooks and appendages though useful indexes of tornadoes are notinfallible guides The appearance ofa hook warns the pilotto stay away butjustbecause the tornado cannot be seen is no assurance that there is no tornado present Expect severe turbulence up to 20 NM away from severe storms this turbulence often has a well defined radar echo boundary This distance decreases somewhat with weaker storms that display less well defined echo boundaries The last section of this manual contains several advisory circulars It is recommended thatthe pilot become
45. 880 DIGITAL WEATHER RADAR CAN ONLY DETECT TURBULENCE WITHIN AREAS OF PRECIPITATION IT CANNOT DE TECT CLEAR AIR TURBULENCE The turbulence detection threshold is moderate turbulence Thatis any area of raindrop motion that is detected as moderate severe or extreme turbulence is displayed in white Areas shown as turbulentare at least moderate turbulence and can be severe extreme or combinations of the three levels of turbulence All three must be avoided Turbulence is most accurately measured within 30 of straight ahead Turbulence measurements outside this area experience reduced accuracy The reduced accuracy results from the effects ofthe antenna scan angle and aircraft motion Levels of turbulence are described in the Airman s Information Manual and are shown in figure 5 34 Radar Facts A28 1146 102 00 5 46 MODERATE SEVERE PRIMUS 88U Digital Weather Radar system REACTION INSIDE INTENSITY AIRCRAFT REACTION AIRCRAFT Turbulence that momentarily causes slight erratic changes in altitude and or attitude pitch roll yaw Turbulence that is similar to light turbulence but of greater intensity Changes in altitude and or attitude occur but the aircraft remains in positive control at all times It usually causes variations in indicated airspeed Turbulence that causes large abrupt changes in altitude and or attitude It usually causes large variations in indicated airspeed Aircraft may be momentarily
46. A 7 do s and don ts of thunderstorm flying A 9 icing A 6 lightning A 8 low ceiling and visibility A 7 schematic cross section of a thunderstorm A 6 squall lines A 4 tornadoes A 5 turbulence A 5 weather radar A 8 icing A 6 lightning A 8 low ceiling and visibility A 7 maximum storm tops A 13 A28 1146 102 01 REV 1 PRIMUS 9880 Digital Weather Radar System Index cont National severe storms laboratory NSSL thunderstorm research A 11 extrapolation to different climbs A 14 hail in thunderstorms A 13 maximum storm tops A 13 modification of criteria when Severe storms and rapid development are evident A 13 relationship between turbulence and altitude A 11 relationship between turbulence and reflectivity A 11 turbulence above storm tops A 12 turbulence and echo intensity on NWS radar WSR 57 A 11 turbulence below cloud base A 12 turbulence in relation to distance from the storm edge A 12 turbulence in relation to distance from storm core A 11 use of airborne radar A 14 visual appearance of storm and associated turbulence with them A 13 purpose A 4 related reading material A 4 squall line A 4 thunderstorm flying A 9 thunderstorm research A 11 tornadoes A 5 turbulence A 5 above storm tops A 12 and altitude A 11 and echo intensity on NWS radar A 11 A28 1146 102 01 REV 1 in relation to distance from storm core A 11 and reflectivity A 1
47. ADAR BEST DETOUR AD 12058 R1 Squall Line Figure 5 27 Radar Facts A28 1146 102 00 5 34 PRIMUS 88U Digital Weather Radar system WEATHER DISPLAY CALIBRATION Ground based radarobservers ofthe National Weather Service NWS currently use video integrator processor VIP levels in reporting thunderstorm intensity levels These radar echo intensity levels are on a scale of one to six Refer to Section 6 of FAA Advisory Circular AC 00 24B for additional details To assistthe pilotin categorizing storms in accordance with VIP levels the indicator display colors representcalibrated rainfall rates in WX and preset calibrated gain The relationship between the 4 color calibrations and the VIP levels is shown in table 5 11 As covered in the RCT description intervening attenuating rainfall reduces the calibrated range and the radar can incorrectly depict the true cell intensity The radar calibration includes a nominal allowance for radome losses Excessive losses in the radome seriously affectradar calibration O ne possible means of verification is signal returns from known ground targets It is recommended that you report evidence of weak returns to ensure thatradome performance is maintained ata levelthatdoes not affect radar calibration To testfor a performance loss note the distance at which the aircraft s base city a mountain or a shoreline can be painted from a given altitude When flying in familiar surroundings v
48. ARGET ALERT T ARM GREEN TGT ALERT YELLOW INVERTED VIDEO TILT ANGLE ALTITUDE COMPENSATED TILT ACT ANNUNCIATION RANGE RING MARKERS MODE 120 DEGREE STBY SCAN SHOWN FSBY TEE COLOR BAR WX WX CALIBRATED GAIN WXIT IVIATRH WX VARIABLE GAIN FLTPLNJ J 112 3 GMAP CALIBRATED GAIN GMAP IVTATR GMAP VARIABLE GAIN NOTE MESSAGES ARE LISTED 12 3 4 T WX T CALIBRATED GAIN IN PRIORITY ORDER VIAIR WX T VAR AD 46694 R2 WI 880 Weather Radar Indicator Display Screen Features Figure 3 3 2 Function Switch A rotary switch used to selectthe following functions e OFF This position turns off the radar system e SBY Standby This position places the radarsystem in standby a ready state with the antenna scan stopped the transmitter inhibited and the display memory erased STBY in white is shown in the mode field If SBY is selected before the initial RTA warmup period is complete approximately 90 seconds the white WAIT legend is shown in the mode field When warmup is complete the system changes the mode field to STBY e WX Weather This position selects the WX mode of operation When WX is selected the system is fully operational and all internal parameters are set for enroute weather detection The alphanumerics are white and WX is shown in the mode field A28 1146 102 00 Operating Controls 3 3 PRIMUS 88U Digital Weather Radar system If WX
49. American National Standards Institute ANSI in their document ANSI C95 1 1982 recommends an exposure level of no more than 5 mW cm Honeywell recommends that operators follow the 5 mW cm standard Figure 6 1 shows MPEL for both exposure levels RADIUS R AIRCRAFT NOSE AND RADOME DIAMETER 10 mW CM 5 mW CM OF FLAT RADIUS R RADIUS R PLATE OF MPEL OF MPEL RADIATOR BOUNDARY BOUNDARY N 5FT 7FT AC 152 CM 213 CM AIRCRAFT LUBBER LINE N 6 FT 9 FT 5 CM 183 CM 275 CM 8 FT 12 FT BOUNDARY 2 244 CM 366 CM 10 5 FT 13 FT 320 CM 396 CM 1D 131612 MPEL Boundary Figure 6 1 A28 1146 102 03 Maximum Permissible Exposure Level MPEL REV 3 6 1 6 2 blank PRIMUS 88U Digital Weather Radar system 7 In Flight Troubleshooting The PRIMUS 880 Digital Weather Radar System can provide troubleshooting information on one of two formats e Fault codes e Textfaults The selection is made atthe time of installation This section describes access and use of this information If the fault codes option is selected they are shown in place of the tilt angle The textfaultoption provides English textin the radartest pattern areas Critical functions in the receiver transmitter antenna RTA are continuously monitored Each fault condition has a corresponding 2 digitfault code FC Additionally a faultname a pilot message and a line maintenance message are associated with each fault condition Fau
50. C X Weert W m Be m Peay 10 000 Y 10 500 FT eee 5 000 10 20 30 40 50 607 70 80 RANGE NAUTICAL MILES AD 17718 R19 Radar Beam Illumination Low Altitude 12 Inch Radiator Figure 5 6 40 000 ANTENNA ADJUSTED FOR 2 8 UPTILT He in 30 000 H z Zz 20 000 LE S LL T 10 000 Nee 5 000 0 7 8 RANGE NAUTICAL MILES AD 17719 Radar Beam Illumination Low Altitude 18 Inch Radiator Figure 5 7 Radar Facts A28 1146 102 00 5 6 PRIMUS 88U Digital Weather Kadar system Tables 5 1 and 5 2 give the approximate tilt settings at which ground targets begin to be displayed on the image periphery for 12 and 18 inch radiators The range atwhich ground targets can be observed is affected by the curvature of the earth the distance from the aircraft to the horizon and altitude above the ground As the tilt control is rotated downward ground targets first appear on the display at less than maximum range NOTE Operation with a 24 inch radiator is similar To find the ideal tilt angle after the aircraftis airborne adjust the TILT control so that groundclutter does notinterfere with viewing of weather targets Usually this can be done by tilting the antenna downward in 1 increments until ground targets begin to appear atthe display periphery Ground returns can be distinguished from strong storm cells by watching for closer ground targets with each small downward increment of tilt The more the dow
51. IRTA AZ POSITION CHK CONTINUOUS RADOME IRTA OVER TEMP RA PULL CONTINUOUS CAU A UN RTA 4839 No SCI Control 20 4911 No ARINC 429 Control NO CNTL IN CHK CHK PROBE CNTL CNTL SRC SRC 4840 AGC Limiting PICTURE CONTINUOUS UNCAL PULL RTA 21 4927 AGC Rx DAC Monitor AGC RADAR POWER ON FAIL In Flight Troubleshooting A28 1146 102 00 Text Faults 7 6 4816 DSP RAM 4817 DSP Video RAM 4855 DSP Watchdog 4900 Mailbox Miscompare 4901 DSP Holda Asserted 4902 DSP Holda not Asserted 4825 Filament Monitor 4827 Severe Magnetron 4829 PFN Trim Monitor 831 Pulse Width w Azimuth Error 5 4836 Over Temp Table 7 2 cont PRIMUS 88U Digital Weather Radar system RCVR PICTURE SELF TEST UNCAL PULL CONTIUOUS RTA 4843 Multiple AFC Unlocks SPOKING LIKELY CONTINUOUS 24 4845 AFC Sweeping AFC PULL RTA 4929 AFC DAC Monitor 4930 AFC Trim DAC Monitor RADAR POWER ON FAIL 4848 AHRS IRS Source HS 429 STAB CHK ATT NSTALLATION UNCAL SRC 4849 DADC Source LS 429 TURB CHK ADC NSTALLATION UNCAL 33 4852 Analog Stab Ref STAB REF STAB CHK ATT NS ON UNCAL RC NSTALLATION NSTALLATION S 34 4853 Scan Switch Off SCAN SWITCH SCAN CHK SWITCH SWITCH 35 4854 Xmit S witch Off XMIT SWITCH XMIT CHK SWITCH SWITCH C 4914 Invalid altitude airspeed stab strapping INVALID RADAR HK STRAPS UNCAL STRAPS 36 4915 Invalid controller source POWER ON strapping 4916 Config1 database v
52. LIGHT PATH THROUGH A FIELD OF STRONG OR VERY STRONG STORMS SEPARATED BY 20 30 MILES OR LESS MAY BE CONSIDERED TO REMAIN FREE FROM SEVERE TURBULENCE A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 13 PRIMUS 88U Digital Weather Radar system EXTRAPOLATION TO DIFFERENT CLIMBS General comment Severe storms are associated with an atmospheric stratification marked by large values of moisture in low levels relative dryness in middle levels and strong wind shear It is well known that this stratification of moisture permits excessive magnitudes of convective instability to exist for an indefinite period until rapid overturning of air is triggered by a suitable disturbance Regions ofthe atmosphere which are either very dry or very moist throughout substantial depths cannot harbor great convective instability Rather a more nearly neutral thermal stratification is maintained partially through a process of regular atmospheric overturning e Desert Areas In desert areas storms should be avoided on the same basis as described in the above paragraphs While nonstorm turbulence may in general be expected more frequently over desert areas during daylight hours than elsewhere THE SAME TURBULENCE CONSIDERATIONS PREVAIL IN THE VICINITY OF THUNDERSTORMS e Tropical Humid Climates When the atmosphere is moist and only slightly unstable though a great depth strong radar echoes may be received from towering cloud
53. PRIMUS 880 Honeywell PILOT S GUIDE Digital Weather Radar System 1D 050282 Honeywell Honeywell International Inc Commercial Electronic Systems 5353 W Bell Rd Glendale Arizona 85308 3912 U S A CAGE 55939 PRIMUS 880 Digital Weather Radar System Pilot s Guide Revised January 2006 Printed in U S A Pub No A28 1146 102 03 September 1996 PRIMUS 66U VIGItal vveamer Kadar System Table of Contents Section 1 INTRODUCTION 000005 2 SYSTEM CONFIGURATIONS 3 OPERATING CONTROLS WI 880 Weather Radar Indicator Operation WC 880 Weather Radar Controller Operation WC 884 Weather Radar Controller Operation Hidden Modes s sss eese Forced Standby Override Roll Offset i ccce cete nen RiollGdalni x nct dh v enr ES Pitch OffSeL imena nie mre Rester Pitch Gaines icc cem eese 4 NORMAL OPERATION Preliminary Control Settings Standby iu meli RUE S Radar Mode Weather Radar Mode Ground Mapping Test Modes rra naem ia cece cece 5 RADAR FACTS uuuuuusesss Radar Operation uuaa Tilt Management auna Stabilization 5 Saget a eee pee Dynamic Error ai hiette e aN a Accelerative Error i a Pitch and Roll Trim Adjustments Stabilization Precheck Roll stabilization check 0004 Pitch offset
54. PROTECTION In weather detection mode storm intensity levels are displayed in four bright colors contrasted against a deep black background Areas of very heavy rainfall appear in magenta heavy rainfall in red less severe rainfall in yellow moderate rainfall in green and little or no rainfall in black background Areas of detected turbulence appear in soft white The antenna sweep position indicator is a yellow bar Range marks and identifying numerics displayed in contrasting colors are provided to facilitate evaluation of storm cells Select the GMAP function to optimize system parameters to improve resolution and enhance identification of small targets at short ranges The reflected signal from ground surfaces is displayed as magenta yellow or cyan mostto least reflective NOTE Section V RadarFacts describes a variety of radaroperating topics It is recommended that you read Section V Radar Facts before learning the specific operational details of the PRIMUS 880 Digital Weather Radar System A28 1146 102 00 Introduction PRIMUS 88U Digital Weather Radar system The radar indicator is equipped with the universal digital interface UDI This feature expands the use of the radar indicator to display information such as checklists short and long range navigation displays when used with a Honeywell DATA NAV system and electrical discharge data from Honeywell s LSZ 850 Lightning Sensor System LSS NOTE Refer t
55. TMENT This in flightadjustmentis made in a bank when the ground returns do not remain symmetrical during turns The procedure is listed in table 5 9 Sw mee 1 If two controllers are installed one must be turned off If an indicator is used as the controller the procedure is the same as given below Fly to an altitude of 10 000 feet AGL or greater Set range to 25 NM Adjust the tilt down until a solid band of ground returns are shown on the screen Then adjust the tilt until the green region of the ground returns start at about 20 NM On the WC controller select variable gain pull WX and REACT OFF VAR shows on the display Select STAB STB 4 times within 3 seconds A display with text instructions is shown 7 From the roll offset entry menu push the STAB STB button twice more to bring up the roll gain entry menu To change the roll gain value pull out the GAIN knob and rotate it The roll gain adjustment range is from 90 to 11096 While flying with a steady roll angle of 10 to 20 adjust for symmetrical display of ground returns When change is completed push in the GAIN knob The display returns to the previous message 11 Push the STAB STB button to go to the next menu pitch gain Roll Gain Adjustment Table 5 9 A28 1146 102 00 Radar Facts 5 29 PRIMUS 88U Digital Weather Radar system PITCH GAIN ADJ USTMENT This in flightadjustmentis made in a bank when the ground returns do n
56. This section contains a word for word transcription of the contents of the following FAA advisory circulars e AC 20 68B e AC 00 24B SUBJECT RECOMMENDED RADIATION SAFETY PRECAUTIONS FOR GROUND OPERATION OF AIRBORNE WEATHER RADAR Purpose This circular sets forth recommended radiation safety precautions to be taken by personnel when operating airborne weather radar on the ground Cancellation AC 20 66A dated April 11 1975 is cancelled Related Reading Material Barnes and Taylor radiation Hazards and Protection London G eorge Newnes Limited 1963 p 211 U S Department of Health Education and Welfare Public Health Service Consumer Protection and Environmental Health Service Environmental health microwaves ultraviolet radiation and radiation from lasers and television receivers An Annotated Bibliography FS 2 300 RH 35 Washington U S Government Printing Office pp 56 57 Mumford W W Some technical aspects of microwave radiation hazards Proceedings of the IRE Washington U S Government Printing Office February 1961 pp 427 447 A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 1 PRIMUS 88U Digital Weather Radar system Background Dangers from ground operation of airborne weather radar include the possibility of human body damage and ignition of combustible materials by radiated energy Low tolerance parts of the body include the eyes and the testis Pr
57. VISIBLE ON RADAR RED ZONE 7 5 WITHIN RAIN AREA RAINFALL RATE RED LEVEL 20 40 60 80 NAUTICAL MILES AD 12057 R2 Radar and Visual Cloud Mass Figure 5 26 As masses of warm moistair are hurled upward to meet the colder air above the moisture condenses and builds into raindrops heavy enough to fall downward through the updraft When this precipitation is heavy enough it can reverse the updraft Between these downdrafts shafts of rain updrafts continue at tremendous velocities It is not surprising therefore that the areas of maximum turbulence are near these interfaces between updraft and downdraft Keep these facts in mind when tempted to crowd a rain shaft or to fly over an innocent looking cumulus cloud A28 1146 102 00 Radar Facts 5 33 PRIMUS 88U Digital Weather Radar system To find a safe and comfortable route through the precipitation area study the radar image of the squall line while closing in on the thunderstorm area In the example shown in figure 5 27 radar observation shows that the rainfall is steadily diminishing on the left while itis very heavy in two mature cells and increasing rapidly in a third cell to the right The safestand mostcomfortable course lies to the left where the storm is decaying into a light rain The growing cell on the right should be given a wide berth AREAS OF MAXIMUM TURBULENCE py CROWING DECAYING CELLS OUTLINE OF RAIN AREA VISIBLE TO R
58. a tilt is automatically adjusted with regard to the selected range and barometric altitude The antenna tilt automatically readjusts with changes in altitude and or selected range In ACT the tilt control can fine tune the autotilt setting by 2 ACT is annunciated with an A following the digital tilt readout The digital tilt readout always shows the commanded tilt of the antenna regardless of the tilt command source ACT command or manual tilt command WARNINGS 1 TO AVOID FLYING UNDER OR OVER STORMS FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH ABOVE AND BELOW YOUR FLIGHT LEVEL 2 ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS A28 1146 102 00 Operating Controls 3 9 PRIMUS 88U Digital Weather Radar system a3 GAIN The GAIN knob is a single turn rotary control and push pull switch that is used to control the receiver gain Push in on the GAIN switch to enter the system into the preset calibrated gain mode Calibrated gain is the normal mode and is used for weather avoidance In calibrated gain the rotary portion of the GAIN control does nothing In calibrated gain the color bar legend is labeled 1 2 3 4 in WX mode or 1 2 3 in GMAP mode Pull out on the GAIN switch to enter the system into the variable gain mode with VAR displayed in the color bar Variable gain is useful for additional weather analysis and for ground mapping In WX mode variable gain can increase receiver sensitivity over the calibrated level to show very
59. ably impossible to adjust it more accurately Pitch and Roll Trim Adjustments The PRIMUS 880 is delivered from the Honeywell factory or repair facility adjusted for correct pitch and roll stabilization and should be ready for use However due to the tolerances of some vertical reference sources you may electto make a final adjustment whenever the radar or vertical reference is replaced on the aircraft or if stabilization problems are observed in flight The four trim adjustments and their effects are summarized in table 5 4 A28 1146 102 00 Radar Facts 5 19 PRIMUS 88U Digital Weather Radar system Trim Adjustment Flight Condition Effect On Ground Return Display Over Level Terrain Roll offset Straight and level Nonsymmetrical display Pitch offset Straight and level Ground displays do not follow contour of range arcs Roll gain Constant roll angle Nonsymmetrical gt 20 display Pitch gain Constant pitch angle Ground displays do 5 not follow contour of range arcs Generally it is recommended to perform trim adjustments only if noticeable effects are being observed Pitch and Roll Trim Adjustments Criteria NOTES 1 Radar Facts 5 20 Table 5 4 Depending on the installation not all of the adjustments shown in table 5 4 are available If STAB TRIM ENABLE programming strap is open only the roll offset adjustment is available If STAB TRIM ENABLE is grounded all four adjustments are ava
60. ail occurs most frequently early in this stage e Inthe thunderstorm s dissipating stage the rain area is largest and shows best with a slight downward antenna tilt Radar can be used to look inside the precipitation area to spot zones of presentand developing turbulence Some knowledge of meteorology is required to identify these areas as being turbulent The most important fact is that the areas of maximum turbulence occur where the most abrupt changes from light or no rain to heavy rain occur The term applied to this change in rate is rain gradient The greater the change in rainfall rate the steeper the rain gradient The steeper the rain gradient the greater the accompanying turbulence More important however is another fact Storm cells are not static or stable but are in a constant state of change While a single thunderstorm seldomlasts more than an hour a squallline shown in figure 5 27 can contain many such storm cells developing and decaying over a much longer period A single cell can startas a cumulus cloud only 1 mile in diameter rise to 15 000 ft grow within 10 minutes to 5 miles in diameter and tower to an altitude of 60 000 feet or more Therefore weather radar should notbe used to take flash pictures of weather but to keep weather under continuous surveillance Radar Facts A28 1146 102 00 5 32 PRIMUS 88U Digital Weather Kadar system AAA_ VISIBLE CLOUD MASS RAIN AREA 4 amp ONLY THIS IS
61. ain corrects the installation atbank angles over 20 for unsymmetrical radar displays Entry Method Selected by sequencing through the roll offset and pitch offset menus with the STAB button Refer to Section 5 Radar Facts table 5 9 Control Pull GAIN knob out and use it Exit Method Push STAB once to continue with the next adjustment Pitch Offset Function Adjusts the pitch attitude of the antenna to allow radar returns in straight and level flight to conform to the radar range rings Entry Method Selected by sequencing through the roll offset menu with the STAB button Refer to Section 5 Radar Facts table 5 8 Control Pull the GAIN knob out and use it Exit Method Push STAB once to continue with the next adjustment Pitch Gain Function Adjusts the gain ifthe radar display is in pitch so that the contour lines track the range lines at higher pitch attitudes A28 1146 102 00 Operating Controls 3 27 PRIMUS 88U Digital Weather Radar system e Entry Method Selected by sequencing through the roll offset pitch offset and roll gain menus with the STAB button Refer to Section 5 Radar Facts table 5 10 e Control Pull the GAIN knob out and use it e Exit Method Push the GAIN knob in Push STAB to exit and Save settings NOTES 1 If installation is configured only for roll offset adjustment pushing the STB button saves and exits after the roll offset adjustment is made 2
62. ardous target is detected the target alert armed annunciation switches to the alert annunciation amber TGT This advisory indicates that a hazardous target is in the aircraft s flightpath and the WX mode should be selected SLV Slave The SLV annunciatoris a dead frontannunciator thatis only used in dual controller installations With dual controllers one controller can be slavedto the other by selecting the RADAR mode switch to OFF onthat controller only This slaved condition is annunciated with the SLV annunciator In the slaved condition both controllers must be off before the radar system turns off 9 MODE The MODE switch is a rotary switch used to select one of the following functions e OFF In this position the radar system is turned off e STBY In this position the radar system is placed in standby a ready state with the antenna scan stopped the transmitter inhibited and the display memory erased STBY in green is displayed in the mode field If STBY is selected before the initial RTA warmup period is complete approximately 45 90 seconds the flashing WAIT legend is displayed in the mode field A28 1146 102 00 Operating Controls 3 23 PRIMUS 88U Digital Weather Radar system When the warmup is complete the system changes the mode field from WAIT to STBY e TEST This position selects the radar test mode A test pattern is displayed to verify that system operates The green TEST legend is d
63. ates that the storm cell has totally attenuated the radar energy and the radar cannot show any additional targets WX or ground behind the cell The cell that produces a radar shadow is a very strong and dangerous cell It should be avoided by 20 miles WARNING DO NOT FLY INTO THE SHADOW BEHIND THE CELL Turbulence Probability The graph ofturbulence probability is shown in figure 5 29 This graph shows the following e Thereis a 10096 probability of lightturbulence occurring in any area of rain e A level one storm all green has virtually no chance of containing severe or extreme turbulence but has between a 5 and 20 chance that moderate turbulence exists e A level two storm one containing green and yellow returns has virtually no probability of extreme turbulence but has a 2096 to 4096 chance of moderate turbulence and up to a 596 chance of severe turbulence e Alevelthree storm green yellow and red radar returns has a 4096 to 85 chance of moderate turbulence a 596 to 10 chance of severe turbulence and a slight chance of extreme turbulence e A level four storm one with a magenta return has moderate turbulence a 10 to 50 chance of severe turbulence and a slight to 2596 chance of extreme turbulence WARNING THE AREAS OF TURBULENCE MAY NOT BE ASSOCIATED WITH THE MAXIMUM RAINFALL AREAS THE PROBABILITIES OF TURBULENCE ARE STATED FOR THE ENTIRE STORM AREA NOT JUST THE HEAVY RAINFALL AREAS Radar Facts A28
64. ating motion it often forms an extremely concentrated vortex from the surface well into the cloud Meteorologists have estimated that wind in such a vortex can exceed 200 knots pressure inside the vortex is quite low The strong winds gather dustand debris and the low pressure generates afunnelshaped cloud extending downward from the cumulonimbus base If the cloud does not reach the surface itis a funnel cloud if it touches the land surface itis a tornado e Tornadoes occur with both isolated and squall line thunderstorms Reports for forecasts of tornadoes indicate that atmospheric conditions are favorable for violent turbulence An aircraft entering a tornado vortex is almostcertain to suffer structural damage Since the vortex extends well into the cloud any pilot inadvertently caught on instruments in a severe thunderstorm could encounter a hidden vortex e Families of tornadoes have been observed as appendages of the main cloud extending several miles outward from the area of lightning and precipitation Thus any cloud connected to a severe thunderstorm carries a threat of violence TURBULENCE e Potentially hazardous turbulence is present in all thunderstorms and a severe thunderstorm can destroy an aircraft Strongest turbulence within the cloud occurs with shear between updrafts and downdrafts Outside the cloud shear turbulence has been encountered several thousand feet above and 20 miles laterally from a severe thunderstorm
65. avoidance pilots should familiarize themselves with FAA Advisory Circular AC 00 24B 1 20 83 Subject Thunderstorms The advisory circular is reproduced in Appendix A of this guide To help the pilot categorize storms as described in the advisory circular referenced above the radar receiver gain is calibrated in the WX mode with the GAIN control in the preset position The radar is not calibrated when variable gain is being used but calibration is restored if RCT TRB or target alert TGT is selected Normal Operation A28 1146 102 03 4 4 REV 3 PRIMUS 9880 Digital Weather Radar System To aid in target interpretation targets are displayed in various colors Each color represents a specific target intensity The intensity levels chosen are related to the National Weather Service NWS video integrated processor VIP levels In the WX mode the system displays five levels as black green yellow red and magenta in increasing order of intensity If RCT is selected the radar receiver adjusts the calibration automatically to compensate for attenuation losses as the radar pulse passes through weather targets on its way to illuminate other targets There is a maximum extent to which calibration can be adjusted When this maximum value is reached REACT compensation ceases At this point a cyan field is added to the display to indicate that no further compensation is possible In the absence of intervening targets the range a
66. be corrected by means of the roll offset function before proceeding figures 5 20 and 5 21 za Refer to the roll offset adjustment procedure in table 5 7 Stabilization In Straight and Level Flight Check Procedure Table 5 5 A28 1146 102 00 Radar Facts 5 21 PRIMUS 88U Digital Weather Radar system AD 17720 R19 Symmetrical Ground Returns Figure 5 19 AD 17721 R19 Ground Return Indicating Misalignment Upper Right Figure 5 20 Radar Facts A28 1146 102 00 5 22 PRIMUS 88U Digital Weather Radar system AD 17722 R19 Ground Return Indicating Misalignment Upper Left Figure 5 21 ROLL STABILIZATION CHECK Once proper operation is established in level flight verify stabilization in a turn using the procedure in table 5 6 eT er O 1 E oc Place the aircraft in 20 roll to the right Note the radar display It should contain appreciably no more returns than found during level flight Figure 5 22 indicates that roll stabilization is inoperative 3 If returns display on the right side of radar indicator the radar system is understabilizing Targets on the left side of the radar display indicate the system is Overstabilizing Refer to table 5 9 for roll gain adjustment NOTE Proper radar operation in turns depends on the accuracy and stability of the installed attitude source Stabilization in Turns Check Procedure Table 5 6 A28 1146 102 00 Radar Facts 5 23
67. ble guides Severe turbulence should be anticipated up to 20 miles from the radar edge of severe storms these often have a well defined radar echo boundary The distance decreases to approximately 10 miles with weaker storms which may sometimes have indefinite radar echo boundaries THEREFORE AIRBORNE RADAR IS A PARTICULARLY USEFUL AID FOR PILOTS IN MAINTAINING A SAFE DISTANCE FROM SEVERE STORMS TURBULENCE ABOVE STORM TOPS Flight data shows a relationship between turbulence above storm tops and the airspeed of upper tropospheric winds WHEN THE WINDS AT STORM TOP EXCEED 100 KNOTS THERE ARE TIMES WHEN SIGNIFICANT TURBULENCE MAY BE EXPERIENCED AS MUCH AS 10 000 FEET ABOVE THE CLOUD TOPS THIS VALUE MAY BE DECREASED 1 000 FEET FOR EACH 10 KNOT REDUCTION OF WIND SPEED This is especially important for clouds whose height exceeds the height of the tropopause It should be noted that flight above severe thunderstorms is an academic consideration for today s civil aircraft in most cases since these storms usually extend up to 40 000 feet and above TURBULENCE BELOW CLOUD BASE While there is little evidence that maximum turbulence exists at middle heights in storms FL 200 300 turbulence beneath a storm is notto be minimized This is especially true when the relative humidity is low in any air layer between the surface and 15 000 feet Then the lower altitudes may be characterized by strong outflowing winds and severe turbulence where thunders
68. cation and electronic navigational equipment Lightning has been suspected of igniting fuel vapors causing explosion however serious accidents due to lightning strikes are extremely rare Nearby lightning can blind the pilot rendering him momentarily unable to navigate by instrument or by visual reference Nearby lightning can also induce permanent errors in the magnetic compass Lightning discharges even distant ones can disrupt radio communications on low and medium frequencies Though lightning intensity and frequency have no simple relationship to other storm parameters severe storms as a rule have a high frequency of lightning WEATHER RADAR Weather radar detects droplets of precipitation size Strength of the radar return echo depends on drop size and number The greater the number of drops the stronger is the echo and the larger the drops the stronger is the echo Drop size determines echo intensity to a much greater extentthan does drop number Hailstones usually are covered with a film of water and therefore actas huge water droplets giving the strongest of all echoes Numerous methods have been used in an attempt to categorize the intensity of a thunderstorm To standardize thunderstorm language between weather radar operators and pilots the use of Video Integrator Processor VIP levels is being promoted The National Weather Service NWS radar observer is able to objectively determine storm intensity levels with VIP e
69. ced in Appendix A of this guide If the system is being used with an EFIS display power up by selecting the weather display on the EHSI Apply power to the radar system using either the indicator or controller power controls Select either Standby or Test mode PRIMUS 880 Power Up Procedure Table 4 1 cont A28 1146 102 03 Normal Operation REV 3 4 1 PRIMUS 88U Digital Weather Radar system Procedure When power is first applied the radar is in WAIT for approximately 90 seconds to allow the magnetron to warm up Power sequences ON OFF ON lasting less than 3 seconds result in a 6 second wait period NOTE If forced standby is incorporated it is necessary to exit forced standby WARNING OUTPUT POWER IS RADIATED IN TEST MODE After the warm up select the Test mode and verify that the test pattern is displayed as shown in figure 4 1 If the radar is being used with an EFIS the test pattern is similar to that shown in figures 4 2 and 4 3 Verify that the yellow antenna position indicator API is shown atthe top of the display 7 Verify that the azimuth marks target alert TGT and sector scan controls are operational PRIMUS 880 Power Up Procedure Table 4 1 wk OUAP rp Me m e SBY N YI m U TS N MAX AD 46699 R1 Indicator Test Pattern 120 Scan WX With TEXT FAULT Enabled Figure 4 1 Normal Operation A28 1146 102 00 4 2 PRIMUS 9880 Digital Weather Radar System
70. d and controls on the indicator are controlled by the dimming bus for the aircraft panel Whenever single or dual radar controllers are used the radar data is displayed on the EFIS MFD or NAV display DEOR PULLVAR TEST ora STBY P GMAP a 03 FPLN A MODE GLV RANGE TILT f iad Q0 Ce SO ee WC 884 Weather Radar Controller Figure 3 5 2 BRT Brightness The BRT switch is a rotary control thatis used to setthe radar raster brightness on the EFIS display 2 TGT Target Alert The TGT switch is an alternate action button that enables and disables the radartargetalertfeature Targetalertis selectable in all but the 300 mile range When selected target alert monitors beyond the selected range and 7 5 on each side ofthe aircraft heading If a return with certain characteristics is detected in the monitored area the target alert changes from the green armed condition to the amber TGT warning condition Refer to the targetalert characteristics in table 3 5 for a target description The amber TGT alerts the pilotas to potentially hazardous targets directly in front and outside of the selected range When the alert is given the pilot should select longer ranges to view the questionable target Target alert is inactive within the selected range Operating Controls A28 1146 102 00 3 20 PRIMUS 88U Digital Weather Radar system Selecting target alert fo
71. d by comparing figures 5 30 and 5 31 If turbulence is present in the precipitation there is a significant change in the raindrop size and or position between the subsequent radar pulses This difference results in a change in the individual return vectors from each raindrop and a commensurate change in the total return vector Therefore if there is a significant difference between pairs of total return vectors for the same range bin that bin contains turbulence and is displayed in white This is illustrated by comparing figures 5 30 and 5 32 The presence ofturbulence is detected by comparing the amplitude of Subsequent total return vectors To measure raindrop motion the turbulence detection circuitry measures the raindrop motion directly toward and away from the antenna Raindrop motion that is perpendicular to the antenna does not produce any doppler effect and cannot be measured by the turbulence detection circuitry For this reason there can be areas of turbulence not detectable by radar or the displayed areas of turbulence can change from antenna scan to antenna scan as the turbulence throws the raindrops in various directions WARNING AREAS OF TURBULENCE CAN NOT ALWAYS BE DETECTED BY THE RADAR A28 1146 102 00 Radar Facts 5 43 PRIMUS 88U Digital Weather Radar system RETURNS FROM EACH RAIN DROP AD 17725 R1 Total Return Vector Figure 5 30 AD 17726 R1 No Turbulence Figure 5 31 Radar Facts A28
72. date 24 looks minute 60 sector scan 4 TGT Target The TGT switch is an alternate action button that enables and disables the radar targetalertfeature Targetalertis selectable in all but the 300 mile range When selected target alert monitors beyond the selected range and 7 5 on each side of the aircraft heading If a return with certain characteristics is detected in the monitored area the target alert changes from the green armed condition to the yellow TGT warning condition This annunciation advises the pilotthat a potentially hazardous targetlies directly in frontand outside of the selected range When this warning is received the pilot should select longer ranges to view the questionable target Note that target alertis inactive within the selected range Operating Controls A28 1146 102 00 3 16 PRIMUS 88U Digital Weather Radar system Selecting target alert forces the system to preset gain Target alert can only be selected in the WX and FP modes In order to activate target alert the target must have the depth and range characteristics described in table 3 4 Selected Range Minimum Target Target Range NM Depth NM NM 5 5 5 55 10 10 60 25 25 75 50 50 100 100 100 150 200 200 250 300 N A FP Flight Plan 5 55 WC 880 Controller Target Alert Characteristics Table 3 4 STB Stabilization The STB button turns the pitch and roll stability ON and OFF Itis also used with the STB
73. description of the test pattern WARNING UNLESS THE SYSTEM IS IN FORCED STANDBY THE TRANSMITTER IS ON AND RADIATING X BAND MICROWAVE ENERGY IN TEST MODE REFER TO SECTION 6 MAXIMUM PERMISSIBLE EXPOSURE LEVEL MPEL AND THE APPENDIX FEDERAL AVIATION ADMINISTRATION FAA ADVISORY CIRCULARS TO PREVENT POSSIBLE HUMAN BODY DAMAGE FSBY Forced Standby FSBY is an automatic nonselectable radar mode As an installation option the indicator can be wired to the weight on wheels WOW squat switch When wired the RTA is in the FSBY mode when the aircraft is on the ground In FSBY mode the transmitter and antenna scan are both inhibited the display memory is erased and the FSBY legend is displayed in the mode field When in the FSBY mode pushing the STAB button 4 times within 3 seconds restores normal operation A28 1146 102 03 Operating Controls REV3 3 5 PRIMUS 88U Digital Weather Radar system WARNING FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERATOR TO ENSURE SAFETY FOR GROUND PERSONNEL 3 TGT Target The TGT button is an alternate action switch that enables and disables the radar targetalert feature Targetalertis selectable in all but the 300 mile range When selected target alert monitors beyond the selected range and 7 5 on each side of the aircraft heading If a return with target alert characteristics is detected in the monitored area the target alert legend changes from the green T armed condition to the
74. dicates that within 20 miles from the center of severe storm cores moderate to severe turbulence is encountered at any altitude about one fifth as often as in the cores of Level 3 or greater thunderstorms Further the data indicates that moderate turbulence is encountered atany altitude up to 10 miles from the center of level 2 thunderstorms SEVERE TURBULENCE IS OFTEN FOUND IN TENUOUS ANVIL CLOUDS 15 TO 20 MILES DOWNWIND FROM SEVERE STORM CORES Our findings agree with meteorological reasoning that THE STORM CLOUD IS ONLY THE VISIBLE PORTION OF A TURBULENT SYSTEM WHOSE UPDRAFTS AND DOWN DRAFTS OFTEN EXTEND OUTSIDE OF THE STORM PROPER A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 11 PRIMUS 88U Digital Weather Radar system TURBULENCE IN RELATION TO DISTANCE FROM THE STORM EDGE THE CLEAR AIR ON THE INFLOW SIDE OF A STORM IS A PLACE WHERE SEVERE TURBULENCE OCCURS Atthe edge ofa cloud the mixing of cloudy and clear air often produces strong temperature gradients associated with rapid variation of vertical velocity Tornado activity is found in a wide range of spacial relationships to the strong echoes with which they are commonly associated but many ofthe mostintense and enduring tornadoes occur on the south to west edges of severe storms The tornado itself is often associated with only a weak echo Echo hooks and appendages are useful qualitative indicators of tornado occurrence but are by no means infalli
75. dly growing storms by 20 miles When severe storms and rapid development are evident the intensity of the radar retum may increase by a huge factor in a matter of minutes Moreover the summit of the storm cells may grow at 7000 ft min The pilot cannot expect a flightpath through such a field of strong storms separated by 20 to 30 NM to be free of severe turbulence Awong all storms showing erratic motion by 20 miles Thunderstorms tend to move with the average wind that exists between the base and top of the cloud Any motion differing from this is considered erratic and may indicate the storm is severe There are several causes of erratic motion They may act individually or in concert Three of the most important causes of erratic motion are 1 Moisture Source Thunderstorms tend to grow toward a layer of very moist air usually south or southeast in the U S in the lowest 1500 to 5000 ft above the earth s surface Moist air generates most of the energy for the storm s growth and activity Thus a thunderstorm may tend to move with the average wind flow around it but also grow toward moisture When the growth toward moisture is rapid the echo motion often appears erratic On atleast one occasion a thunderstorm echo moved in direct opposition to the average wind Disturbed Wind Flow Sometimes thunderstorm updrafts block winds near the thunderstorm and act much like a rock in a shallow river bed This pillar of updraft forces
76. dure 5 23 5 7 In flight Roll Offset Adjustment Procedure 5 25 5 8 Pitch Offset Adjustment Procedure 5 28 5 9 Roll Gain Adjustment sseseuuse 5 29 5 10 Pitch Gain Adjustment sssssse 5 30 5 11 Display Levels Related to VIP Levels Typical 5 36 5 12 Severe Weather Avoidance Procedures 5 60 5 13 TILT Setting for Maximal Ground Target Display 12 Inch Radiator 2 cece eee eee 5 70 5 14 TILT Setting for Maximal Ground Target Display 18 Inch Radiator 0 eee eee 5 71 7 1 Fault Data Fields seusssss 7 3 2 Text FAUS o i acne pe EROR RR meant y 7 5 7 3 Pilot MessageS seres 7 8 B 1 EGPWS Obstacle Display Color Definitions B 4 Table of Contents A28 1146 102 01 TC 6 REV 1 PRIMUS 88U Digital Weather Radar system l Introduction The PRIMUS 880 Digital Weather Radar System is a lightweight X band digital radar with alphanumerics designed for weather detection WX and ground mapping GMAP The primary purpose of the system is to detect storms along the flightpath and give the pilot a visual indication in color of their rainfall intensity and turbulence content After proper evaluation the pilot can chart a course to avoid these storm areas WARNING THE SYSTEM PERFORMS THE FUNCTIONS OF WEATHER DETECTION OR GROUND MAPPING IT SHOULD NOT BE USED NOR RELIED UPON FOR PROXIMITY WARNING OR ANTICOLLISION
77. e turn rotary control and push pull switch that is used to controlthe receiver gain When the GAIN switch is pushed the System enters the preset calibrated gain mode Calibrated gain is the normal mode and is used for weatheravoidance In calibrated gain the rotary portion of the GAIN control does nothing Whenthe GAIN switchis pulled out the system enters the variable gain mode Variable gain is useful for additional weather analysis and for ground mapping In WX mode variable gain can increase receiver sensitivity over the calibrated level to show weak targets or it can be reduced below the calibrated level to eliminate weak returns A28 1146 102 00 Operating Controls 3 25 PRIMUS 88U Digital Weather Radar system WARNING WHEN LOW SETTINGS OF VARIABLE GAIN ARE USED HAZARDOUS TARGETS CAN BE ELIMINATED FROM THE DISPLAY In the GMAP mode variable gain is used to reduce the level of the typically very strong returns from ground targets Minimum gain is with the control at its full ccw position Gain increases as the control is rotated in a cw direction from full ccw At the full cw position the gain is at maximum The VAR legend annunciates variable gain Selecting RCT or TGT forces the system into preset gain Preset gain is not annunciated HIDDEN MODES The PRIMUS 880 has five hidden modes that are summarized as follows e Forced Standby FSBY Override e Roll Offset e Roll Gain NOTE e Pitch Offset NOTE e
78. e weather targets can no longer be calibrated The point where red level weather target calibration is no longer possible is highlighted by changing the background field from black to cyan Any area of cyan background is an area where attenuation has caused the receiver gain to reach its maximum value so further calibration of returns is not possible Extreme caution is recommended in any attempt to analyze weather in these cyan areas The radar cannot display an accurate picture of what is in these cyan areas Cyan areas should be avoided NOTE f the radar is operated such that ground targets are affecting REACT they could cause REACT to provide invalid indications Any target detected inside a cyan area is automatically forced to a magenta color indicating maximum severity Figure 5 28 shows the same storm with REACT OFF and with REACT ON Radar Facts A28 1146 102 00 5 38 PRIMUS 88U Digital Weather Radar system AD 46705 R1 wx WAP gp PULL SBY 4 SG E WAU n MAX REACT REACT ON and OFF Indications Figure 5 28 A28 1146 102 00 Radar Facts 5 39 PRIMUS 88U Digital Weather Radar system Shadowing An operating technique similar to the REACT blue field is shadowing To use the shadowing technique tilt the antenna down until ground is being painted just in front of the storm cell s An area of no ground retums behind the storm cell has the appearance of a shadow behind the cell This shadow area indic
79. e 0 C they begin to melt and precipitation may reach the ground as either hail orrain Rain atthe surface does not mean the absence of hail aloft You should anticipate possible hail with any thunderstorm especially beneath the anvil of a large cumulonimbus Hailstones larger than one half inch in diameter can significantly damage an aircraft in a few seconds LOW CEILING AND VISIBILITY Generally visibility is near zero within a thunderstorm cloud Ceiling and visibility may also be restricted in precipitation and dust between the cloud base and the ground The restrictions create the same problem as all ceiling and visibility restrictions but the hazards are increased many fold when associated with other thunderstorm hazards of turbulence hail and lightning which make precision instrument flying virtually impossible EFFECT ON ALTIMETERS Pressure usually falls rapidly with the approach of a thunderstorm then rises sharply with the onset of the first gust and arrival of the cold downdraft and heavy rain showers falling back to normal as the storm moves on This cycle of pressure change may occur in 15 minutes If the pilot does not receive a corrected altimeter setting the altimeter may be more than 100 feet in error A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 7 PRIMUS 88U Digital Weather Radar system LIGHTNING A lightning strike can puncture the skin of an aircraft and can damage communi
80. e mail address e Make sure that you get the next revision of this guide Honeywell Product Support A28 1146 102 03 8 2 REV3 PRIMUS 9880 Digital Weather Radar System 9 Abbreviations ABBREVIATION AC ACT ADC AFC AGC AGL AHRS ANLG ANSI API ATT AZ BITE BRT CCW CHK CLR CNTL CONFIG CRC CRT CW DADC DSP EFIS EGPWS EHSI EL FAA FC A28 1146 102 03 REV3 i Acronyms and abbreviations used in this guide are defined as follows EQUIVALENT Advisory Circular Altitude Compensated Tilt Air Data Computer Automatic Flight Control Automatic Gain Control Above Ground Level Attitude Heading Reference System Analog American National Standards Institute Antenna Position Indicator Attitude Azimuth Built in Test Equipment Brightness Counterclockwise Check Clear Control Configuration Cyclic Redundancy Check Cathode Ray Tube Clockwise Digital Air Data Computer Display Electronic Flight Instrument System Enhanced Ground Proximity Warning System Electronic Horizontal Situation Indicator Elevation Federal Aviation Administration Fault Code Abbreviations PRIMUS 9880 Digital Weather Radar System FLTPLN FP FPLN FMS FPGA FSBY ft GCR GMAP GPS hr HVPS INHIB IO IOP IN IRS kt kts LEWP LSS LX MFD mm MON MPEL NAV ND NM NSSL NWS OSC PPI PPP Abbreviations 9 2 Flight Plan Flight Management System Field Programmable Gate Array
81. e that the signal to color conversion circuits are operating normally The maintenance function lets the pilot or the line maintenance technician determine the major fault areas The fault data can be displayed in one of two ways selected atthe time of installation e TEXT FAULT A plain English text indicating the failure is placed in the test band e Fault code A fault code is displayed refer to the maintenance manual for an explanation The indicator or EFIS display indicates a fault as noted below e Dedicated Radar Indicator A FAIL annunciation is shown atthe top left corner of the test pattern It indicates that the built in test equipment BITE circuitry is detecting a malfunction The exact nature ofthe malfunction can be seen by selecting TEST Refer to Section 7 In Flight Troubleshooting Normal Operation A28 1146 102 00 4 6 PRIMUS 88U Digital Weather Radar system e EFIS MFD ND Faults are normally shown when test is selected NOTES 1 Some weather failures on EFIS are annunciated with an amber WX 2 Some EFIS installations can power up with an amber WX if weather radar is turned off 3 Ifthe fault code option is selected they are shown with the FAIL annunciation e g FAIL 13 A28 1146 102 00 Normal Operation 4 7 4 8 blank PRIMUS 88U Digital Weather Radar system 5 RadarFacts RADAR OPERATION The PRIMUS 880 Digital Weather Radar works on an echo principle The radar sends ou
82. ean wind increases speed and often produces large hail and extreme turbulence Merging Echoes Merging echoes sometimes become severe but often the circulation of the merging cells interfere with each other preventing intensification The greatest likelihood of aviation hazards is at the right rear section of the echo Severe Weather Avoidance Procedures Table 5 12 cont A28 1146 102 00 Radar Facts 5 59 PRIMUS 88U Digital Weather Radar system Step Procedure Never continue flight towards or into a radar shadow or the blue REACT field WARNING STORMS SITUATED BEHIND INTERVENING RAIN FALL MAY BE MORE SEVERE THAN DEPICTED ON THE DISPLAY If the radar signal can penetrate a storm the target displayed seems to cast a shadow with no visible returns This indicates that the storm contains a great amount of rain that attenuates the sanal and prevents the radar from seeing beyond the cell under observation The REACT blue field shows areas where attenuation could be hiding severe weather Both the shadow and the blue field are to be avoided y 20 miles Keep the REACT blue field turned on The blue field will form fingers that point towards the stronger cells Severe Weather Avoidance Procedures Table 5 12 Configurations of Individual Echoes Northern Hemisphere Sometimes a large echo will develop configurations which are associated with particularly severe aviation hazards Several of these are discu
83. earned the studies continue because much is not known Knowledge and weather radar have modified attitudes toward thunderstorms but one rule continues to be true any storm recognizable as a thunderstorm should be considered hazardous until measurements have shown it to be safe That means safe for you and your aircraft Almost any thunderstorm can spell disaster for the wrong combination of aircraft and pilot Hazards A thunderstorm packs just about every weather hazard known to aviation into one vicious bundle Although the hazards occur in numerous combinations letus look atthe mosthazardous combination of thunderstorm the squall line then we will examine the hazards individually SQUALL LINES A squallline is a narrow band ofactive thunderstorms Often itdevelops on or ahead of a cold front in moist unstable air but it may develop in unstable air far removed from any front The line may be too long to detour easily and too wide and severe to penetrate It often contains steady state thunderstorms and presents the single most intense weather hazard to aircraft It usually forms rapidly generally reaching maximum intensity during the late afternoon and the first few hours of darkness Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 PRIMUS 88U Digital Weather Radar system TORNADOES e The most violent thunderstorms draw into their cloud bases with greatvigor Ifthe incoming air has any initial rot
84. ecautions Management and supervisory personnel should establish procedures for advising personnel of dangers from operating airborne weather radars on the ground Precautionary signs should be displayed in affected areas to alert personnel of ground testing GENERAL e Airborne weather radar should be operated on the ground only by qualified personnel e Installed airborne radar should not be operated while other aircraft is in the hangar or other enclosure unless the radartransmitter is not operating or the energy is directed toward an absorption shield which dissipates the radio frequency energy Otherwise radiation within the enclosure can be reflected throughout the area BODY DAMAGE To prevent possible human body damage the following precautions should be taken e Personnelshould never stand nearby and in frontofa radar antenna which is transmitting When the antenna is notscanning the danger increases e A recommended safe distance from operating airborne weather radars should be established A safe distance can be determined by using the equations in Appendix 1 or the graphs of figures 1 and 2 This criterion is now accepted by many industrial organizations and is based on limiting exposure of humans to an average power density not greater than 10 milliwatts per square centimeter e Personnelshould be advised to avoid the end of an open waveguide unless the radar is turned off e Personnel should be advised to avoid loo
85. echnique called Pulse Pair Processing PPP The PPP technique used in the new PRIMUS 880 Digital Weather Radar is adapted from the proven technique used in the earlier PRIMUS Weather Radars In the turbulence detection mode of operation the PRIMUS 880 Digital Weather Radar transmits about 1400 pulses per second with a power of 10 kW The pulse pair processor compares the returns from successive pulses to determine the presence of turbulence i e the return from pulse one is compared to the return from pulse two pulse two s return is compared to pulse three s and so on Since the processor is comparing the returns from two subsequent pulses a pair it was given the name pulse pair processor To perform the comparison the radar first divides the selected range into 128 equal parts with each part called a range bin The radar compares the return data in each range bin for the first pulse with the return data in each range bin for the second pulse For example the data returned from pulse one in range bin 34 is compared to the data returned from pulse two in range bin 34 This process continues throughout the entire area covered by the radar all range bins and a turbulence decision is made for each range bin When turbulence is detected in any bin the color of that bin is made white The return data being compared is the total return vector TRV TRV is the vector sum of the return from each raindrop contained within the range bin In
86. ed On Ground Figure 7 3 In Flight Troubleshooting A28 1146 102 00 7 4 PRIMUS 88U Digital Weather Radar system Fault Code and Text Fault Relationships Table 7 2 lists the relationship between e Fault codes FC e Pilot Maintenance Messages e Fault Name type description cross reference XREF 4809 OP top codecrc CRC 4810 FLASH CRC RADAR PULL POWER ON FAIL RTA 4904 Config Table CRC Config Table CRC CRC 4846 ADC Reference CONTINUOUS 4903 IOP Ready RADAR PULL FAIL RTA 4908 Int ARINC 429 POWER ON Loopback 4910 Spurious ARINC Interrupt L CONTINUOUS ARINC 429 In Coupling L POWER ON 4806 EEPROM Timer CRC POWER ON 4811 EEPROM POC L POWER ON 4842 Stab Trim CRC POWER ON Calibration CRC 4812 OP Mailbox Mailbox DSP Mailbox MAILBOX RAM POWER ON 4813 Timing FPGA RAM Timing FPGA RAM RAM Timing FPGAREG Timing FPGAREG REG 05 48 IO FPGA RAM FPGA RADAR PULL POWER ON FAIL RTA Text Faults Table 7 2 cont 4 A28 1146 102 00 In Flight Troubleshooting 7 5 PRIMUS 88U Digital Weather Radar system 4828 FPGA Download 4906 IO FPGA REG 4847 STC Monitor STC DAC RADAR PULL POWER ON FAIL RTA 07 4830 HVPS Monitor HVPS MON RADAR PULL CONTINUOUS FAIL RTA RADAR PULL FAIL RTA POWER ON MAGNETRON RADAR L LATCHED FAIL HVPS MON CONTINUOUS PULSE WIDTH RADAR PULL CONTINUOUS UNCAL RTA CH 4832 Elevation Error EL POSITION TILT K CONTINUOUS UNCA RADOME
87. ed and is active When INHIB is annunciated EGPWS is not displayed on the radar indicator and the aural annunciators do not sound NOTE TheFAIL and INHIB annunciators are often incorporated into the INHIB push button e TERR Terrain The TERR annunciator indicates that the annunciator lamp power is on It does not indicate the operational status of the system e ON The ON annunciator indicates that the radar indicator is displaying terrain This ON push button lamp is lit if the ON push button has been pushed and is active or if an actual Terrain Alert is indicated by the EGPWS system and the terrain is automatically displayed NOTE The TERR and ON annunciators are often incorporated into the ON push button Some installation may not contain all of these controls and annunciators or they may have different names Most EGPWS installations have additional controls and or annunciators i e TEST Refer to the appropriate publication for details Enhanced Ground Proximity Warning System EGPWS A28 1146 102 03 B 2 REV 3 Use or disclosure of the information on this page is subject to the restrictions on the title page of this document PRIMUS 9880 Digital Weather Radar System Related EGPWS System Operation Some installations may have a DATA NAV navigation display and or checklist lightning sensor system LSS and or traffic alert and crew alerting system TCAS that already share the radar indicator s display by wa
88. ents ssesesee esee Typical PRIMUS 880 Digital Weather Radar Display i rete ERERU Ier MIR TER WI 880 Weather Radar Indicator Front Panel VIOW ds evade wer EI xe ess WI 880 Weather Radar Indicator Display Screen Features eree one ete iin Maeda eats WC 880 Weather Radar Controller Configurations WC 884 Weather Radar Controller Indicator Test Pattern 120 Scan WX With TEXT FAULT Enabled 0 c cece een eee EFIS Test Pattern Typical 120 Scan Shown WX discuss eae i E RP CURE OE haste WI 880 Indicator Test Pattern With TEXT FAULT Enabled bep re der Pme 2 5 3 1 3 2 3 3 3 11 3 20 4 2 4 3 4 4 Table of Contents TC 3 PRIMUS 9880 Digital Weather Radar System Table of Contents cont List of Illustrations cont Figure Page 5 1 Positional Relationship of an Airplane and Storm Cells Ahead as Displayed on Indicator 5 2 5 2 Antenna Beam Slicing Out Cross Section of Storm During Horizontal Scan ssuuuuue 5 3 5 3 Sea Returns useselessseeseesss 5 4 5 4 Radar Beam Illumination High Altitude 12 Inch Radiator 0 cee eee ee eee 5 5 5 5 Radar Beam Illumination High Altitude 18 Inch Radiator 0 eee ee eee 5 5 5 6 Radar Beam Illumination Low Altitude 12 Inch Radiator 0 eee ee eee 5 6 5 7 Radar Beam Illumination Low Altitude 18 Inch Radiator cee eee eee 5 6 5 8 Ideal Tilt Angle 0
89. erify thatlandmarks can still be painted atthe same distances Any loss in performance results in the system notpainting the reference target atthe normal range A28 1146 102 00 Radar Facts 5 35 PRIMUS 88U Digital Weather Radar system REFLECTIVITY VIDEO INTEGRATED PROCESSOR DISPLAY RAINFALL RAINFALL TEGRATED PROCE RATE RATE LEVEL MM HR IN HR STORM VIP RATE MMR CATEGORY LEVEL IN HR EXTREME GREATER GREATER deena THAN DM 50 INTENSE VERY STRONG 4 12 0 17 0 5 il E m Ed SCREEN 0 04 0 17 LESS THAN Eus espere WEAK BLACKI THE THRESHOLD eed THE VIP LEVELS CAN BE REALIZED WHEN THERE IS NO INTERVENING RADAR SIGNAL ATTENUATION WITH RCT SELECTED RCT BLUE FIELD OCCURS WHEN THE MINIMUM RED LEVEL DETECTED IS BELOW SYSTEM SENSITIVITY AD 17926 R5 Display Levels Related to VIP Levels Typical Table 5 11 NOTE The radar is calibrated for convective weather Stratiform storms ator near the freezing level can show high reflectivity Do not penetrate such targets Radar Facts A28 1146 102 00 5 36 PRIMUS 88U Digital Weather Radar system VARIABLE GAIN CONTROL The PRIMUS 880 Digital Weather Radar variable gain control is a single turn rotary control and a push pull switch that is used to control the radar s receiver gain With the switch pushed in the system is in the preset calibrated gain mode In calibrated gain the rotary control does nothing When the GAIN switch is
90. ersion size mismatch RADAR PULL FAIL RTA Text Faults Table 7 2 A28 1146 102 00 In Flight Troubleshooting 7 1 PRIMUS 88U Digital Weather Radar system Table 7 3 describes the pilot messages B ENNEE RADAR FAIL The radar is currently inoperable and should not be relied upon It will need to be replaced or repaired at the next opportunity RADAR CAUTION A failure has been detected that can compromise the calibration accuracy of the radar Information from the radar should be used only for advisory purposes such as ground mapping for navigation PICTURE UNCAL The radar functions are ok but receiver calibration is degraded Color level calibration should be assumed to be incorrect Have the RTA checked atthe next opportunity TILT UNCAL An error in the antenna position system has been detected The displayed tilt angle setting could be incorrect This may also cause ground spoking Have the RTA checked atthe next opportunity TURB UNCAL A problem has been detected with the turbulence detection hardware Assume turbulence display to be inaccurate Nonturbulence modes should be functioning properly Have the RTA checked at the next opportunity SPOKING LIKELY A problem has been detected which may cause spoking to occur Have the system checked at the next opportunity STAB UNCAL An error in the antenna positioning system has been detected Groundspoking or excessive ground returns du
91. f sliced bread standing on end From a point close to the surface of earth it towers to a high altitude summit Withoutupsetting the loaf of bread the radar removes a single slice from the middle of the loaf and places this slice flat upon the table Looking atthe slice of bread from directly above a cross section of the loaf can be seen in its broadest dimension In the same manner the radar beam literally slices out a horizontal cross section of the storm and displays it as though the viewer was looking Radar Facts A28 1146 102 00 5 2 PRIMUS 88U Digital Weather Radar system atitfrom above as shownin figure 5 2 The heightofthe slice selected for display depends upon the altitude and also upon the upward or downward TILT adjustment made to the antenna ANTENNA THUNDERSTORM THUNDERSTORM AD 17716 R1 Antenna Beam Slicing Out Cross Section of Storm During Horizontal Scan Figure 5 2 Weather radar can occasionally detect other aircraft but it is not designed for this purpose and should never be considered a collision avoidance device Nor is weather radar specifically designed as a navigational aid but it can be used for ground mapping by tilting the antenna downward Selecting the GMAP mode enhances returns from ground targets A28 1146 102 00 Radar Facts 5 3 PRIMUS 88U Digital Weather Radar system When the antenna is tilted downward for ground mapping two phenomena may occurthatcan confuse the pilot
92. familiar with them Radar Facts A28 1146 102 00 5 68 PRIMUS 88U Digital Weather Radar System GROUND MAPPING Ground mapping operation is selected with the GMAP button An example of ground map display is shown in figure 5 49 Turn the TILT control down until the desired amount of terrain is displayed The degree of down tiltwill depend upon the type ofterrain aircraftaltitude and selected range Tables 5 13 and 5 5show tiltsettings for maximal ground target display at selected ranges MOST REFLECTIVE LEAST REFLECTIVE MODERATELY REFLECTIVE AD 37252 R1 Ground Mapping Display Figure 5 49 For the low ranges 5 10 25 and 50 NM the transmitter pulsewidth is narrowed and the receiver bandwidth is widened to enhance the identification of small targets In addition the receiver STC characteristics are altered to better equalize ground target reflections versus range As a result the preset gain position is generally used to display the desired map The pilot can manually decrease the gain to eliminate unwanted clutter A28 1146 102 00 Radar Facts 5 69 PRIMUS 88U Digital Weather Radar system 40 000 TILT LIMITED REGION LINE OF SIGHT LIMITED REGION AD 35710 TILT Setting for Maximal Ground Target Display 12 Inch Radiator Table 5 13 NOTE The line of sight distance is nominal Atmospheric conditions and terrain will offset this value Radar Facts A28 1146 102 00 5
93. he dual configuration gives the appearance of having two radar systems on the aircraft In the dual configuration the pilot and copilot each select independent radar mode range tilt and gain settings for display on their respective display The dual configuration time shares the RTA Onthe right to leftantenna scan the system switches to the mode range tilt and gain selected by the left controller and updates the left display On the reverse antenna scan the system switches to the mode range tilt and gain setting selected by the right controller and updates the right display Either controller can be slaved to the other controller to show identical images on both sides of the cockpit NOTE When WAIT SECTOR SCAN or FORCED STANDBY are activated the radar operates as if in single controller configuration This is an exception to the ability of each pilot to independently select modes A28 1146 102 00 System Configurations 2 1 PRIMUS 88U Digital Weather Radar system STAND ALONE CONFIGURATION INDICATOR WI 880 Monerwell D scT atiyO SINGLE OR DUAL EFIS OPTION EFIS ONLY CONFIGURATION CONTROLLER WC 880 772 OMI Xp IES 4 4 _ _ __ pun Why CRT Dev j Ecc d 4 l i 1 ES Jt sese J s Cor JED iue s u OPTIONAL SINGLE OR DUALEFIS 2ND CONTROLLER EFIS MFD CONFIGURATION
94. he ground returns start at about 20 NM On the WC controller select RCT OFF Select STAB STB 4 times within 3 seconds A display with text instructions will be displayed See figure 5 23 The radar unitis in the roll offset adjustment mode Pull outthe GAIN knob to make a roll offset adjustment See figure 5 24 for a typical display The offset range is from 2 0 to 2 0 and is adjustable by the GAIN knob The polarity of the GAIN knob is such that clockwise rotation of the knob causes the antenna to move down when scanning on the right side While flying straight and level adjust the GAIN knob until ground clutter display is symmetrical Push in the GAIN knob When the GAIN knob is PM in the display returns to the previous In flight Roll Offset Adjustment Procedure Table 5 7 cont A28 1146 102 00 Radar Facts 5 25 PRIMUS 88U Digital Weather Radar system sw Pande 10 Push the STAB STB button to go to the next menu pitch offset NOTE Onceset the roll compensation is stored in nonvolatile memory in the RTA Itis remembered when the system is powered down In flight Roll Offset Adjustment Procedure Table 5 7 Honeywell AD 49018 R2 Roll Offset Adjustment Display Initial Figure 5 23 Radar Facts A28 1146 102 00 5 26 PRIMUS 88U Digital Weather Radar system T A p GAIN amp MINK S S MAX AD 49017 R1 Roll Offset Adjustment Display Final Figure 5 24
95. hile weight is on wheels the system returns to the forced standby mode A28 1146 102 00 Operating Controls 3 15 PRIMUS 88U Digital Weather Radar system 2 TILT The TILT switch is a rotary control that is used to select the tilt angle of antenna beam with relation to the horizon CW rotation tilts beam upward 0 to 15 ccw rotation tilts beam downward 0 to 15 The range between 5 and 5 is expanded for ease ofsetting A digital readout of the antenna tilt angle is displayed on the EFIS e PULL ACT Altitude Compensated Tilt Function When the TILT control knob is pulled out the system engages the ACT option In ACT the antenna tilt is automatically adjusted with regard to the selected range and barometric altitude The antenna tilt automatically readjusts with changes in altitude and or selected range In ACT the tilt control can fine tune the tilt setting by 2 ACT is annunciated with an A following the digital tilt readout The digital tilt readout always shows the commanded tilt of the antenna regardless of the tilt command source ACT command or manual tilt command WARNINGS 1 TO AVOID FLYING UNDER OR OVER STORMS FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH ABOVE AND BELOW YOUR FLIGHT LEVEL 2 ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS 3 SECT Scan Sector The SECT switch is an alternate action button that is used to select either the normal 12 looks minute 120 scan or the faster up
96. ilable Consult the installation configuration information for details After any adjustment procedure is completed monitor the ground returns displayed by the radar during several pitch and roll maneuvers Verify that the ground returns stay somewhat constant during changes in aircraft orientations If not repeat the adjustment procedure After the trim adjustment feature is selected more than one adjustment can be made They are available in the sequence shown in table 5 4 and can be done in the sequence of first finishing one adjustment then proceeding to do the next by pushing the STAB button A28 1146 102 00 PRIMUS 88U Digital Weather Radar system Stabilization Precheck Prior to performing any of the adjustment procedures conduct the precheck procedures listed in tables 5 5 and 5 6 LEVEL FLIGHT STABILIZATION CHECK Check stabilization in level flight using the procedure in table 5 5 se retry IU Trim the aircraft for straight and level flight in smooth Clear air over level terrain LE wu Select the 50 mile range 3 Rotate the tilt control upward until all ground returns disappear Rotate the tilt downward until ground returns just begin to show After several antenna sweeps verify that ground returns are equally displayed figure 5 19 If returns are only on one side of the radar screen or uneven across the radar screen a misalignment of the radar antenna mounting is indicated This problem can
97. ion might be indicated by the appearance of nonexisting targets The radome can also cause refractive distortion which would make it appear that the TILT control was out of adjustment or that bearing indications were somewhat erroneous A radome with ice or water trapped within its walls can cause significant attenuation and distortion of the radar signals This type of attenuation cannot be detected by the radar even with REACT on but it can in extreme cases cause blind spots If a target changes significantly in Size shape or intensity as aircraft heading or attitude change the radome is probably the cause Radar Facts A28 1146 102 00 5 54 PRIMUS 88U Digital Weather Kadar System WEATHER AVOIDANCE Figure 5 41 illustrates a typical weather display in WX mode Recommended procedures when using the radar for weather avoidance are given in table 5 12 The procedures are given in bold face explanations of the procedure follow in normal type face LIGHT RAINFALL MODERATE RAINFALL HEAVY RAINFALL SEVERE RAINFALL AD 37250 R1 Weather Display Figure 5 41 A28 1146 102 00 Radar Facts 5 55 PRIMUS 88U Digital Weather Radar system Step Procedure 1 Keep TGT alert enabled when using short ranges to be alerted if a new storm cell develops in the 2 aircraft s flightpath Keep the gain in nes The gain control should be in preset except for brief periods when variable gain is used f
98. is selected before the initial RTA warmup period is over approximately 90 seconds the white WAIT legend is displayed in the mode field In wait mode the transmitter and antenna scan are inhibited and the display memory is erased When the warmup is complete the system automatically switches to the WX mode The system in preset gain is calibrated as listed in table 4 1 Rainfall Rate Color Rainfall Rate Color Coding Table 3 1 e GMAP Ground Mapping The GMAP position puts the radar system in the ground mapping mode The system is fully operational and all parameters are set to enhance returns from ground targets NOTE REACT TGT or TURB modes are not selectable in GMAP WARNING WEATHER TYPE TARGETS ARE NOT CALIBRATED WHEN THE RADAR IS IN THE GMAP MODE BECAUSE OF THIS DO NOT USE THE GMAP MODE FOR WEATHER DETECTION As a constant reminder that GMAP is selected the alphanumerics are changed to green the GMAP legend is shown in the mode field and the color scheme is changed to cyan yellow and magenta Cyan represents the least reflective return yellow is a moderate return and magenta is a strong return If GMAP is selected before the initial RTA warmup period is complete the white WAIT legend is shown in the mode field In wait mode the transmitter and antenna scan are inhibited and the memory is erased When the warmup period is complete the system automatically switches to the GMAP mode e FP FlightP
99. isplayed in the mode field Refer to Section 4 Normal O peration for a description of the test pattern WARNING UNLESS THE SYSTEMIS IN FORCED STANDBY THE TRANSMIT TER IS ON AND RADIATING X BAND MICROWAVE ENERGY IN TEST MODE REFER TO SECTION 6 MAXIMUM PERMISSI BLE EXPOSURE LEVEL MPEL e WX In this position the radar system is fully operational and all internal parameters are set for enroute weather detection If WX is selected before the initial RTA warmup period is complete a flashing WAIT legend is displayed In WAIT mode the transmitter and antenna scan are inhibited and the memory is erased When the warmup is complete the system automatically switches to the WX mode and a green WX is displayed in mode field The system in preset gain is calibrated given in table NO TAG Rainfall Rate Color Rainfall Rate Color Coding Table 3 6 e GMAP Selecting GMAP places the radar system in the ground mapping mode The system is fully operational and all internal parameters are set to enhance returns from ground targets RCT compensation is inactive WARNING WEATHER TYPE TARGETS ARE NOT CALIBRATED WHEN THE RADAR IS IN THE GMAP MODE BECAUSE OF THIS DO NOT USE THE GMAP MODE FOR WEATHER DETECTION Operating Controls A28 1146 102 00 3 24 PRIMUS 88U Digital Weather Radar system When GMAP is selected a green GMAP legend is displayed and the color scheme is changed to cyan yellow magenta Cyan represen
100. king into a waveguide or into the open end of a coaxial connector or line connector to a radar transmitter output as severe eye damage may result Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 PRIMUS 88U Digital Weather Radar system e Personnel should be advised that when high power radar transmitters are operated out of their protective cases X rays may be emitted Stray X rays may emanate from the glass envelope type pulser oscillator clipper or rectifier tubes as well as magnetrons COMBUSTIBLE MATERIALS To prevent possible fuel ignition an insulated airborne weather radar should not be operated while an aircraft is being refueled or defueled M C Beard Director of Airworthiness A28 1146 102 00 Federal Aviation Administration FAA Advisory Circulars A 3 PRIMUS 88U Digital Weather Radar system SUBJECT THUNDERSTORMS Purpose This advisory circular describes the hazards of thunderstorms to aviation and offers guidance to help prevent accidents caused by thunderstorms Cancellation Advisory Circular 00 24A dated J une 23 1978 is cancelled Related Reading Material Advisory Circulars 00 6A Aviation Weather 090 45B Aviation Weather Services 00 50A Low Level Wind Shear General We all know what a thunderstorm looks like Much has been written aboutthe mechanics and life cycles ofthunderstorms They have been studied for many years and while much has been l
101. lan TheFP position puts the radarsystemin the flight plan mode which clears the screen of radar data so ancillary data can be displayed Examples of this data are Operating Controls A28 1146 102 00 3 4 PRIMUS 9880 Digital Weather Radar System e FP Flight Plan The FP position puts the radar system in the flight plan mode which clears the screen of radar data so ancillary data can be displayed Examples of this data are Navigation displays Electrical discharge lightning data NOTE In the FP mode the radar RTA is put in standby the alphanumerics are changed to cyan and the FLTPLN legend is shown in the mode field The target TGT alert mode can be used in the FP mode With target alert on and the FP mode selected the target alert armed annunciation green TGT is displayed The RTA searches for a hazardous target from 5 to 55 miles and 7 5 of the aircraft heading No radar targets are displayed If a hazardous target is detected the target alert armed annunciation switches to the alert annunciation yellow TGT This advises the pilot that a hazardous target is in his flightpath and the WX mode should be selected to view it NOTE The TGT function is inoperative when a checklist is displayed e TST Test The TST position selects the radar test mode A special test pattern is displayed to verify system operation The TEST legend is shown in the mode field Refer to Section 4 Normal Operations for a
102. last atleast 5 minutes and are less than 25 miles in diameter The favored location for hook echoes is to the right rear of a large and strong cell however in rare cases tornadoes occur with hooks in other parts ofthe cell AVOID V NOTCH BY 20 MILES A large isolated echo will sometimes have the configuration that is shown in figure 5 43 This echo is called V notch or flying eagle although some imagination may be needed by the reader to see the eagle V notch echoes are formed by the wind pattern at the leading edge left front of the echo Thunderstorm echoes with V notches are often severe containing strong gusty winds hail or funnel clouds butnotallV notches indicate severe weather Again severe weather is most likely at S in figure 5 43 echo movement AD 15561 R1 V Notch Echo Pendant Shape Figure 5 43 Radar Facts A28 1146 102 00 5 62 PRIMUS 88U Digital Weather Radar system AVOID PENDANT BY 20 MILES The pendant shape shown in figure 5 44 represents one of the most severe storms the supercell One study concluded that in supercells e The average maximum size of hail is over 2 inches 5 3 cm e The average width of the hail swath is over 12 5 miles 20 2 km e Sixty percent produce funnel clouds or tornadoes The classic pendant shape echo is shown in figure 5 44 Note the general pendant shape the hook and the steep rain gradient This storm is extremely dangerous and must be avoided
103. lective liquid water The figures that follow show the relationship between flight situations and the correcttiltangle The first describes a high altitude situation the second describes a low altitude situation e The ideal tilt angle shows a few ground targets at the edge of the display see figure 5 8 Ramm a GROUND ea RETURN AD 35694 Ideal Tilt Angle Figure 5 8 e Earth s curvature can be a factor if altitude is low enough or if the selected range is long enough as shown in figure 5 9 E m GROUND a RETURN AD 35695 Earth s Curvature Figure 5 9 A28 1146 102 00 Radar Facts 5 11 PRIMUS 88U Digital Weather Radar system e Convective thunderstorms become much less reflective above the freezing level This reflectivity decreases gradually over the first 5000 to 10 000 feet above the freezing level as shown in figure 5 10 On FREEZING LEVEL AD 35696 Convective Thunderstorms Figure 5 10 The aircraft in figure 5 10 has a clear radar indication of the thunderstorm probably with a shadow in the ground returns behind it e If the tilt angle shown in figure 5 11 is not altered the thunderstorm appears to weaken as the aircraft approaches it T FREEZING LEVEL AD 35697 Unaltered Tilt Figure 5 11 Radar Facts A28 1146 102 00 5 12 PRIMUS 88U Digital Weather Radar system e Proper tilt management demands that tilt be changed continually when approaching haza
104. lence are the principal obstacles to a safe and comfortable flight Neither of these conditions is directly visible on radar The radar shows only the rainfall patterns with which these conditions are associated The weather radar can see water best in its liquid form as shown in figure 5 25 not water vapor notice crystals not hail when small and perfectly dry It can see rain wet snow wet hail and dry hail when its diameter is about 8 10 of the radar wavelength or larger At X band this means that dry hail becomes visible to the radar at about 1 in diameter REFLECTIVE LEVELS WILL NOT REFLECT WET HAIL GOOD VAPOR RAIN GOOD o 0 ODO SMALL DRY HAIL DRY HAIL POOR hoo B DRY SNOW VERY POOR AD 46704 R19 r Qee O Weather Radar Images Figure 5 25 A28 1146 102 00 Radar Facts 5 31 PRIMUS 88U Digital Weather Radar system The following are some truths about weather and flying as shown in figure 5 26 e Turbulence results when two air masses at different temperatures and or pressures meet e This meeting can form a thunderstorm e The thunderstorm produces rain e The radar displays rain thus revealing the turbulence e n the thunderstorm s cumulus stage echoes appear on the display and grow progressively larger and sharper The antenna can be tilted up and down in small increments to maximize the echo pattern e n the thunderstorm s mature stage radar echoes are sharp and clear h
105. lts can be accessed on the ground or while airborne The following conditions indicate that fault information is being displayed e Display indicator or RTA malfunction e FAIL annunciation on weather indicator or EFIS display If the feature TEXT FAULTS is enabled the radar test pattern area will display plan English text fault information If itis not enabled only the fault code is shown one ata time on the indicator or EFIS display A28 1146 102 00 In Flight Troubleshooting 7 1 PRIMUS 88U Digital Weather Radar system NOTES 1 FC installations with a radar indicator can display stored faults for the current power on cycle and nine previous cycles Installations with radar displayed on the electronic flight instrument system EFIS do not display stored faults In FC installation thatuse a radar indicator when the storage memory is full the indicator fault storage deletes the oldest power onfault codes to make room for the newest In EFIS installations some weather failures are only annunciated with an amber WX In EFIS installations with TEXT FAULTS enabled the fault codes are also presented as part of the FAIL annunciation e g FAIL 13 Test Mode With TEXT FAULTS Enabled Upon entering test mode the most recent fault is displayed cycling to the oldest fault in the eligible list of faults Upon reaching the lastfault an END OF LIST message is displayed To recycle through the list again exit and
106. n in soft white The turbulence threshold is five meters per second WARNINGS 1 TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF RAINFALL THE PRIMUS 880 DIGITAL WEATHER RADAR SYSTEM CANNOT DETECT CLEAR AIR TURBULENCE 2 UNDETECTED TURBULENCE CAN EXIST WITHIN ANY STORM CELL REFER TO SECTION 5 RADAR FACTS OF THIS GUIDE FOR ADDITIONAL INFORMATION Selecting the 100 200 or 300 mile range turns off turbulence detection The T is deleted from the mode annunciation Subsequently selecting ranges of 50 miles or less re engages turbulence detection A description of the turbulence detection capabilities and limitations is given in Section 5 Radar Facts of this guide 7 RANGE The RANGE buttons are two momentary contact buttons used to select the operating range of the radar The range selections are from 5 to 300 NM full scale In FP mode additional ranges of 500 and 1000 NM are available The up arrow selects increasing ranges and the down arrow selects decreasing ranges Each of the five range rings on the display has an associated marker that annunciates its range AZ Azimuth The AZ button is an alternate action switch that enables and disables the electronic azimuth marks When enabled azimuth marks at 30 intervals are displayed The azimuth marks are the same color as the other alphanumerics 9 SCT Scan Sector Operating Controls A28 1146 102 03 3 8 REV3 PRIMUS 88U Digital Weather Radar system BRT
107. ncreases A28 1146 102 00 Radar Facts 5 37 PRIMUS 88U Digital Weather Radar system Honeywell has incorporated attenuation compensation that adjusts the receiver gain by an amount equal to the amount of attenuation That is the greater the amount of attenuation the higher the receiver gain and thus the more sensitive the receiver Attenuation compensation continuously calibrates the display of weather targets regardless of the amount of attenuation With attenuation compensation weather target calibration is maintained throughout the entire range of a single cell The cell behind a cell remains properly calibrated making proper calibration of weather targets at long ranges possible e Cyan REACT Field Fromthe description of attenuation it can be seen that high levels of attenuation caused by cells with heavy rainfall causes the attenuation compensation circuitry to increase the receiver gain ata fast rate Low levels of attenuation caused by cells with low rainfall rates cause the receiver gain to increase ata slower rate The receiver gain is adjusted to maintain target calibration Since there is a maximum limit to receiver gain strong targets high attenuation levels cause the receiver to reach its maximum gain value in a short time short range Weak or no targets low attenuation levels cause the receiver to reach its maximum gain value in a longer time longer range Once the receiver reaches its maximum gain valu
108. nstalled The system permits selection of ranges in WX mode from 5 to 300 NM full scale In the flight plan FPLN mode additional ranges of 500 and 1000 miles are permitted The up arrow selects increasing ranges while the down arrow selects decreasing ranges One half the selected range is annunciated at the one half scale range mark on the EHSI NOTE Some Integrated avionics systems incorporate radar range with the map display range control on a MFD ND display GAIN The GAIN is a single turn rotary control and push pull switch that is used to control the receiver gain When the GAIN switch is pushed the System enters the preset calibrated gain mode Calibrated gain is the normal mode and is used for weather avoidance In calibrated gain the rotary portion of the GAIN control does nothing When the GAIN switch is pulled out the system enters the variable gain mode Variable gain is useful for additional weather analysis and for ground mapping In WX mode variable gain can increase receiver sensitivity over the calibrated level to show weak targets or it can be reduced below the calibrated level to eliminate weak returns Operating Controls A28 1146 102 03 3 18 REV3 PRIMUS 88U Digital Weather Radar system WARNING LOW VARIABLE GAIN SETTINGS CAN ELIMINATE HAZARDOUS TARGETS FROM THE DISPLAY In GMAP mode variable gain is used to reduce the level of strong returns from ground targets Minimum gain is attained with the c
109. nward tilt the closer the ground targets that are displayed When ground targets are displayed move the tilt angle upward in 1 increments until the ground targets begin to disappear Proper tilt adjustmentis a pilotjudgment buttypically the besttiltangle lies where ground targets are barely visible or just off the radar image Tables 5 1 and 5 2 give the approximate tilt settings required for different altitudes and ranges If the altitude changes or a different range is selected adjustthe tilt control as required to minimize ground returns A28 1146 102 00 Radar Facts 5 7 PRIMUS 88U Digital Weather Radar system a W EZ ZO dg He E MEE Een EE KARA LINE OF SIGHT LIMITED REGION AD 29830 R2 Approximate Tilt Setting for Minimal Ground Target Display 12 Inch Radiator Table 5 1 Tiltangles shown are approximate Where the tiltangle is notlisted the operator must exercise good judgment NOTE Theline of sight distance is nominal Atmospheric conditions and terrain offsetthis value Radar Facts A28 1146 102 00 5 8 PRIMUS 88U Digital Weather Radar system 40 000 sm 9 L3 8 EE TILT LIMITED REGION LINE OF SIGHT LIMITED REGION 2 000 1 000 AD 35710 Approximate Tilt Setting for Minimal Ground Target Display 18 Inch Radiator Table 5 2 Tiltangles shown are approximate Where the tilt angle is notlisted the operator must exercise good judgment NOTE Theline
110. o Honeywell Pub 28 1146 54 LSZ 850 Lightning Sensor System Pilot s Handbook for more information Introduction A28 1146 102 00 1 2 PRIMUS 88U Digital Weather Radar system 2 System Configurations The PRIMUS 880 Digital Weather Radar System can be operated in many configurations to display weather or ground mapping information on a radar indicator electronic flight instrument system EFIS display multifunction display MF D or on a combination of these displays The various system configurations are summarized in the following paragraphs and shown in figure 2 1 NOTE Other configurations are possible but not illustrated The stand alone configuration consists of two units receiver transmitter antenna RTA and a dedicated radar indicator In this configuration the radar indicator contains all the controls to operate the PRIMUS 880 Digital Weather Radar System A single or dual Honeywell EFIS can be added to the stand alone configuration In such a case the electronic horizontal situation indicator EHSI repeats the data displayed on the radar indicator System control remains with the radar indicator The second system configuration uses an RTA and single or dual controllers The single or dual EFIS is the radar display Since there is no radar indicator in this configuration the radar system operating controls are located on the controller With a single controller all cockpit radar displays are identical T
111. of sightdistance is nominal Atmospheric conditions and terrain offsetthis value A28 1146 102 00 Radar Facts 5 9 PRIMUS 88U Digital Weather Radar system Altitude Sight Feet o5 10 25 5 10 25 50 100 200 NM 40 000 EXE 246 35 000 ENS 230 30 000 4 2 3 213 25 000 REGIONE EXE XE 195 20 000 TJI 174 15 000 4 1 0 E 151 10 000 a ee ale a WE 123 5 000 ea ee INE E 87 4 000 6 2 0 1 fe 78 3 000 aie See a 2 67 2 000 TUBAE EE i 55 1 000 aielo Ei aa 39 500 8 m a H 27 AD 50232 Approximate Tilt Setting for Minimal Ground Target Display 24 Inch Radiator Table 5 3 Tilt angles shown are approximate Where the tilt angle is not listed the operator must exercise good judgement NOTE Radar Facts 5 10 The line of sight distance is nominal Atmospheric conditions and terrain offset this value A28 1146 102 00 PRIMUS 88U Digital Weather Radar system Tilt management is often misunderstood It is crucial to safe operation of airborne weather radar If radar tiltangles are not properly managed weather targets can be missed or underestimated The upper levels of convective storms are the mostdangerous because of the probability of violent windshears and large hail But hail and winshear are not very reflective because they lack ref
112. on Compensation Technique This switch position turns on RCT The REACT circuitry compensates for attenuation of the radar signal as it passes through rainfall The cyan field indicates areas where further compensation is not possible Any target detected within the cyan field cannot be calibrated and should be considered dangerous All targets in the cyan field are displayed as 4th level precipitation magenta RCT is a submode of the WX mode and selecting RCT forces the system to preset gain When RCT is selected the RCT legend is displayed on the EFIS MFD A28 1146 102 00 Operating Controls 3 13 PRIMUS 88U Digital Weather Radar system NOTES 1 REACT s three functions attenuation compensation cyan field and forcing targets to magenta are switched on and off with the RCT switch 2 Refer to Section 5 Radar Facts for a description of REACT e GMAP Ground Mapping The GMAP position puts the radar system in the Ground Mapping mode The system is fully operational and all parameters are set to enhance returns from ground targets NOTE REACT TGT or TRB modes are not selectable in GMAP WARNING WEATHER TYPE TARGETS ARE NOT CALIBRATED WHEN THE RADAR IS IN THE GMAP MODE BECAUSE OF THIS DO NOT USE THE GMAP MODE FOR WEATHER DETECTION As a constant reminder that GMAP is selected the alphanumerics are changed to green the GMAP legend is displayed in the mode field and the color scheme is changed to cyan
113. ontrol at its full ccw position Gain increases as the control is rotated in a cw direction from full ccw at full cw position the gain is at maximum The VAR legend annunciates variable gain Selecting RCT or TGT forces the system into calibrated gain 9 SLV Slave The SLV annunciator is only used in dual controller installations With dual controllers one controller can be slaved to the other by selecting OFF on that controller only with the RADAR mode switch This slaved condition is annunciated with the SLV annunciator In the slaved condition both controllers must be off before the radar system turns off LSS Lightning Sensor System Option The LSS switch is an optional four position rotary switch that selects the LSS operating modes described below e OFF In this position all power is removed from the LSS e SBY Inthis position the display of LSS data is inhibited butthe LSS still accumulates data e LX Inthis position the LSS is fully operational and it displays LSS data on the indicator e CLR TST In this position accumulated data is cleared from the memory of the LSS After 3 seconds the test mode is initiated in the LSS A28 1146 102 00 Operating Controls 3 19 PRIMUS 88U Digital Weather Radar system WC 884 WEATHER RADAR CONTROLLER OPERATION The controls and display features of the WC 884 Weather Radar Controller are indexed and identified in figure 3 5 Brightness levels for all legen
114. or detailed analysis Immediately after the analysis switch back to preset gain WARNING DO NOTLEAVE THE RADAR IN VARIABLE GAIN SIG NIFICANT WEATHER MAY NOT BE DISPLAYED Any storm with reported tops at or greater than 20 000 feet must be avoided by 20 NM WARNING DRY HAIL CAN BE PREVALENT AT HIGHER ALTI TUDES WITHIN NEAR OR ABOVE STORM CELLS AND SINCE ITS RADAR REFLECTIVITY IS POOR IT MAY NOT BE DETECTED Use increased gain rotate GAIN control to its maximum cw position when flying near storm tops This helps display the normally weaker returns that could be associated with hail Severe Weather Avoidance Procedures Table 5 12 cont Radar Facts A28 1146 102 00 5 56 PRIMUS 88U Digital Weather Radar system Step Procedure When flying at high altitudes tilt downward frequently to avoid flying above storm tops Studies by the National Severe Storms Laboratory NSSL of Oklahoma have determined that thunderstorms extending to 60 000 ft show little variation of turbulence intensity with altitude Ice crystals are poor reflectors Rain water atthe lower altitudes produce a strong echo however at higher altitudes the nonreflective ice produces a week echo as the antenna is tilted up Therefore though the intensity of the echo diminishes with altitude it does not mean the severity of the turbulence has diminished NOTE Ifthe TILT control is left in a fixed position at the higher flight levels a sto
115. orkmanship and conformity to Type Design and to certify that the article meets all controlling documentation Reconditioned Specification criteria are on file at Honeywell facilities and are available for review All exchange units are updated with the latest performance reliability MODs on an attrition basis while in the repair cycle For more information regarding the SPEX program including maintenance pricing warranty support and access to an electronic copy of the Exchange Rental Program for Corporate Operators Pub No A65 8200 001 you can go to the Honeywell web site at http www avionicsservices com home jsp A28 1146 102 03 Honeywell Product Support REV 3 8 1 PRIMUS 9880 Digital Weather Radar System CUSTOMER SUPPORT Honeywell Aerospace Online Technical Publications Web Site Go to the Honeywell Online Technical Publications Web site at https pubs cas honeywell com to e Download or view publications online e Order a publication e Tell Honeywell of a possible data error in a publication Customer Response Center CRC If you do not have access to the Honeywell Online Technical Publications Web site send an e mail message or a fax or speak to a person at the CRC e E mail cas publications distribution honeywell com e Fax 1 602 822 7272 e Phone 1 877 484 2979 USA e Phone 1 602 436 0272 International Also the CRC is available if you need to e Identify a change of address telephone number or
116. ot follow the contours of the range arcs during turns The procedure is listed in table 5 10 m eee o O m o mem If two controllers are installed one must be turned off If an indicator is used as the controller the procedure is the same as given below BEEN Fly to an altitude of 10 000 feet AGL or greater Set range to 25 NM Adjust the tilt down until a solid band of ground returns are shown on the screen Then adjust the tilt until the rd region of the ground returns start at about 20 NM On the WC controller select variable gain pull W and REACT OFF VAR shows on the display Push STAB STB 4 times within 3 seconds A display with text instruction is shown From the roll offset entry menu push the STAB STB button 3 more times to bring up the pitch gain entry menu To change the pitch gain value pull out the GAIN knob and rotate it The pitch gain adjustment range is from 90 to 11096 While flying with a steady pitch angle of gt 5 adjust so the contour of the ground returns follow the contour of the range arcs as closely as possible When change is completed push in the GAIN knob The display returns to the previous message Push the STAB button to exit the mode and save the value in nonvolatile memory Pitch Gain Adjustment Table 5 10 Radar Facts A28 1146 102 00 5 30 PRIMUS 88U Digital Weather Radar system INTERPRETING WEATHER RADAR IMAGES From a weather standpoint hail and turbu
117. pe ground based radar and with newly developed doppler radar The following comments are based on NSSL s interpretation of information and experience from this research RELATIONSHIP BETWEEN TURBULENCE AND REFLECTIVITY Weather radar reflects precipitation such as rain and hail turbulence It has been found however that the intensity level of the precipitation reflection does correlate with the degree of turbulence in a thunderstorm The most severe turbulence is not necessarily found at the same place that gives the greatest radar reflection RELATIONSHIP BETWEEN TURBULENCE AND ALTITUDE The NSSL studies of thunderstorms extending to 60 000 feet show little variation of turbulence intensity with altitude TURBULENCE AND ECHO INTENSITY ON NWS RADAR WSR 57 The frequency and severity of turbulence increases with radar reflectivity a measure of the intensity of echoes from storm targets at a standard range Derived gust velocities exceeding 2 100 feet per minute classified as severe turbulence are commonly encountered in level 3 storms In level 2 storms gusts of intensity between 1 200 and 2 100 feet per minute classified as moderate turbulence are encountered approximately once for each 10 nautical miles of thunderstorm flight TURBULENCE IN RELATION TO DISTANCE FROM STORM CORE NSSL data indicates that the frequency and severity of turbulence encounters decrease slowly with distance from storm cores Significantly the data in
118. play as itis approached The pilot should notbe fooled into believing the storm has dissipated as the aircraftapproaches it The possibility exists that the radiated energy is being directed from the aircraft antenna above the storm as the aircraft gets closer If this is the case the weather shows up again when the antenna is tilted downward as little as 1 Assuming thata storm has dissipated during the approach can be quite dangerous if this is not the case the turbulence above a storm can be as severe as that inside it Radar Facts A28 1146 102 00 5 50 PRIMUS 88U Digital Weather Kadar system OVERFLYING A STORM AD 12061 R10 Overshooting a Storm Figure 5 38 Another example ofthe pilot s importance in helping the radar serve its safety comfort purpose is shown in figure 5 39 This is the blind alley or box canyon situation Pilots can find themselves in this situation if they habitually fly with the radar on the short range The short range returns show an obvious corridor between two areas of heavy rainfall but the long range setting shows the trap Both the near and far weather zones could be avoided by a short term course change of about45 to the right Always switch to long range before entering such a corridor A28 1146 102 00 Radar Facts 5 51 PRIMUS 88U Digital Weather Radar system THE BLIND ALLEY Cn TS LONG RANGE SHORT RANGE AD 12062 R1 Short and Long Blind Alley Figure 5
119. pulled out the system enters the variable gain mode Variable gain is useful for additional weather analysis In the WX mode variable gain can increase receiver sensitivity over the calibrated level to show very weak targets or it can be reduced below the calibrated level to eliminate weak returns WARNING LOW VARIABLE GAIN SETTINGS CAN ELIMINATE HAZARDOUS TARGETS RAIN ECHO ATTENUATION COMPENSATION TECHNIQUE REACT Honeywell s REACT feature has three separate butrelated functions e Attenuation Compensation As the radar energy travels through rainfall the raindrops reflecta portion ofthe energy back toward the airplane This results in less energy being available to detect raindrops atgreater ranges This process continues throughoutthe depth of the storm resulting in a phenomenon known as attenuation The amount of attenuation increases with an increase in rainfallrate and with an increase in the range traveled through the rainfall i e heavy rain over a large area results in high levels of attenuation while light rain over a small area results in low levels of attenuation Storms with high rainfall rates can totally attenuate the radar energy making itimpossible to see a second cell hidden behind the firstcell In some cases attenuation can be so extreme that the total depth of a single cell cannot be shown Without some form of compensation attenuation causes a single cell to appear to weaken as the depth of the cell i
120. que REACT 5 37 azimuth resolution 5 53 hail size probability 5 47 shadowing 5 40 spotting hail 5 48 turbulence detection operation 5 45 turbulence detection theory 5 42 turbulence probability 5 40 stabilization 5 18 accelerative error 5 18 dynamic error 5 18 tilt management 5 5 variable gain control 5 37 weather avoidance 5 55 severe weather avoidance procedures 5 60 weather display calibration 5 35 Radar Images 5 31 Radar operation 5 1 Radiation Safety Precautions A 1 Radome 5 54 Rain echo attenuation compensation technique REACT 5 37 Recommended radiation safety precautions for ground operation of airborne weather radar A 1 background A 2 cancellation A 1 precautions A 2 body damage A 2 combustible materials A 3 general A 2 purpose A 1 related reading material A 1 pitch gain adjustment 5 30 pitch offset adjustment 5 28 roll gain adjustment 5 29 roll stabilization check 5 23 5 25 variable gain control 5 37 Stabilization precheck 5 21 System configurations 2 1 2 2 S Shadowing 5 40 Stabilization 5 18 Index Index 4 1 Test mode 4 6 color bands 4 7 dedicated radar indicator 4 7 fault code 4 7 EFIS MFD ND 4 7 noise band 4 6 target alert block 4 6 text fault 4 6 Thunderstorms A 4 effect on altimeters A 7 extrapolation to different climbs A 14 general A 4 hail A 7 hail in A 13 hazards of A 4 effect on altimeters A 7 hail
121. quipment These radar echo intensity levels are on a scale of one to six If the maximum VIP levels are 1 weak and 2 moderate then light to moderate turbulence is possible with lightning VIP Level 3 is strong and severe turbulence is possible with lightning VIP Level 4 is very strong and severe turbulence is likely with lightning VIP Level 5 is intense with severe turbulence lightning hail likely and organized surface wind gusts VIP Level 6 is extreme with severe turbulence lightning large hail extensive wind gusts and turbulence Thunderstorms build and dissipate rapidly Therefore do not attempt to plan a course between echoes The best use of ground radar information is to isolate general areas and coverage of echoes You must avoid individual storms from in flight observations either by visual sighting or by airborne radar It is better to avoid the whole thunderstorm area than to detour around individual storms unless they are scattered Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 PRIMUS 88U Digital Weather Radar System Airborne weather avoidance radar is as its name implies for avoiding severe weather notfor penetrating it Whether to fly into an area of radar echoes depends on echo intensity spacing between the echoes and the capabilities of you and your aircraft Remember that weather radar detects only precipitation drops it does not detect turbulence Therefore the radar scope p
122. r Radar System NOTES 1 ON is used to indicate any selected radar mode 2 SLV means that displayed data is controlled by opposite side controller 3 XXX 2 means that display is controlled by appropriate on side control for the antenna sweep direction associated with that control 2 implies two controllers are on 4 n standby the RTA is centered in azimuth with 15 upward tilt Video data is suppressed The transmitter is inhibited 5 The MFD if used can repeat either left or right side data depending upon external switch selection Equipment covered in this guide is listed in table 2 2 and shown in figure 2 2 Cockpit Mounted Options WI 880 Weather Radar Indicator 7007700 401 402 403 404 WC 880 Weather Radar Controller 7008471 4XX WC 884 Weather Radar Controller 7006921 815 816 Remote Mounted Equipment WU 880 Receiver Transmitter Antenna 7021450 801 NOTE Typically either the indicator or one of the remote controllers one or two is installed PRIMUS 880 Weather Radar Equipment List Table 2 2 System Configurations A28 1146 102 03 2 4 REV3 PRIMUS 88U Digital Weather Radar system c z 00 9 8 D gt O C D O O C WI 880 INDICATOR WC 880 CONTROLLER AD 46691 Typical PRIMUS 880 Weather Radar Components Figure 2 2 A28 1146 102 00 System Configurations 2 5 2 6 blank
123. r the tilt setting must not be left at this setting Periodically the pilot should look up and down from this setting to see the total picture of the weather in the flightpath Often hailstorms generate weak but characteristic patterns like those shown in figure 5 37 Fingers or hooks of cyclonic winds that radiate from the main body of a storm usually contain hail A U shaped pattern is also frequently a column of dry hail that returns no signal but is buried in a larger area of rain thatdoes return a strong signal Scalloped edges on a pattern also indicate the presence of dry hail bordering a rain area Finally weak or fuzzy protuberances are not always associated with hail but should be watched closely they can change rapidly DOWNWARD TILT POSITION WET HAIL AND RAIN AD 12059 R1 Rain Coming From Unseen Dry Hail Figure 5 36 A28 1146 102 00 Radar Facts 5 49 PRIMUS 88U Digital Weather Radar system FINGER HOOK U SHAPE AD 357130 Familiar Hailstorm Patterns Figure 5 37 The more that is learned about radar the more the pilot is an all importantpart ofthe system The proper use of controls is essential to gathering all pertinent weather data The proper interpretation ofthat data the displayed patterns is equally importantto safety and comfort This point is illustrated again in figure 5 38 When flying at higher alitudes a storm detected on the long range setting can disappear from the dis
124. range and the aircraft s barometric attitude ACT adjusts the tiltto show a few ground targets atthe edge ofthe display In ACT the ideal setting can be adjusted 2to accommodate terrain height or pilot preferences NOTE Since ACT uses air data computer barometric altitude to adjust the tilt operating near high altitude airports or even high terrain can resultin a lower than desired tiltangle In such cases use of the manual tilt is recommended To calculate the tilt angle the weather radar uses the air data computer s barometric altitude with reference to an assumed ground level of 2000 feet above sea level This assumed ground levelis a factor during low altitude flight especially when flying in mountainous areas The ground targets that are usually at the edge of the display tend to migrate to the middle of the display This also happens when longer ranges 200 NM to 300 NM are selected and the altitude is such that the earth s curvature is a factor In ACT the range control can be used to sweep the beam along the ground to look for storms at various ranges as shown in figure 5 18 ACT is best suited for high altitude operation while in the weather surveillance mode i e aircraft is in cruise and there is no weather within 100 NM The operator can then use the range control to frequently sweep the beam down to avoid overflying any fast developing storms Atlower altitudes manual tiltshould be used to frequently sweep above and
125. ration are equal As long as the acceleration force persists the gyroscope precesses toward a false gravity position at the rate of approximately 2 min The radar follows the gyroscope into error at the same rate When the acceleration force ceases the gyroscope precesses back to true gravity erection at the same rate Radar Facts A28 1146 102 00 5 18 PRIMUS 88U Digital Weather Radar system Some vertical gyroscopes have provisions for deactivating the roll erection torque motor whenever the airplane banks more than approximately 6 to reduce the effect of lateral acceleration during turns To some extent stabilization error is displayed in the radar image after any speed change and or turn condition If the stabilization system seems to be in error because the radar begins ground mapping on one side and not the other or because it appears that the tilt adjustment has slipped verify that aircrafthas been in nonturning constant speed flight long enough to allow the gyroscope to erect on true earth gravity When dynamic and acceleration errors are taken into account maintaining accuracy of 1 2 of 1 orless is notalways possible Adjust the antenna tilt by visually observing the ground return Then slowly tiltthe antenna upward until terrain clutter no longer enters the display exceptatthe extreme edges If ground display is observed onone side but not on the other the stabilization system is somewhat in error but itis prob
126. rces the system into preset gain Target alert can be selected in the WX and FP modes To activate target alert the target must have the depth and range characteristics described in table 3 5 Selected Range Minimum Target Target Range NM Depth NM NM 10 5 10 60 25 25 75 50 50 100 5 5 100 5 100 150 5 200 200 250 300 N A FP Flight Plan 5 55 WC 884 Controller Target Alert Characteristics Table 3 5 3 STB Stabilization The STAB button is a that turns the pitch and roll stabilization ON and OFF This radar is normally attitude stabilized It automatically compensates for roll and pitch maneuvers refer to Section 5 Radar Facts for a description of stabilization The amber STB annunciator appears on the screen Itis also used with the STB adjust mode and to override forced standby 4 RCT Rain Echo Attenuation Compensation Technique Selecting RCT forces the system to presetgain When RCT is selected the green REACT legend is displayed in the mode field The RCT circuitry compensates for attenuation of the radar signal as it passes through rainfall The cyan field indicates areas where further compensation is not possible Any target detected within the cyan field cannot be calibrated and should be considered dangerous All targets in the cyan field are displayed as fourth level precipitation magenta NOTE Refer to Section 5 Radar Facts for a description of REACT A28 1146 102 00
127. rdous weather so that ground targets are not painted by the radar beam as shown in figure 5 12 Tu FREEZING LEVEL AD 35698 Proper Tilt Technique Figure 5 12 e After heading changes in a foul weather situation the pilot should adjust the tilt to see what was broughtinto the aircraft s flightpath by the heading changes as shown in figure 5 13 DISPLAY BEFORE TURN DISPLAY AFTER TURN THUNDERSTORM WAS OUT OF DISPLAY BEFORE TURN AND IS NOW UNDER BEAM AD 30429 Tilt Management With Heading Changes Figure 5 13 A28 1146 102 00 Radar Facts 5 13 PRIMUS 88U Digital Weather Radar system e Under the right conditions a dangerous thunder bumper can develop in 10 minutes and can in factspawn and mature under the radar beam as the aircraft approaches it as shown in figure 5 14 If flying at 400 kt groundspeed a fast developing thunderstorm that spawns 67 NM in frontofthe aircraft can be large enough to damage the aircraft by the time it arrives at the storm Tu ese NOR MTR ES AS IT APPROACHES FREEZING LEVEL AD 35699 Fast Developing Thunderstorm Figure 5 14 e Atlow altitude the tilt should be setas low as possible to get ground returns at the periphery only as shown in figure 5 15 CORRECT WRONG FREEZING LEVEL a A AAA AD 35700 Low Altitude Tilt Management Figure 5 15 Excess up tiltshould be avoided as itcan illuminate weather above the freezing level
128. ring roll maneuvers may occur This may be due either to the RTA or the source of pitch and roll information to the RTA NO AUTOTILT No altitude information is available to make the altitude compensated tilt calculation Otherwise the unit may be operated as normal Have system including altitude source checked at the next opportunity SCAN SWITCH The SCAN SWITCH located on the RTA is off disabling the antenna scan Check atthe next opportunity XMIT SWITCH The XMIT switch located on the RTA is off disabling the transmitter Check at the next opportunity Pilot Messages Table 7 3 In Flight Troubleshooting A28 1146 102 00 7 8 PRIMUS 9880 Digital Weather Radar System 8 Honeywell Product Support The Honeywell SPEX program for corporate operators provides an extensive exchange and rental service that complements a worldwide network of support centers An inventory of more than 9 000 spare components assures that the Honeywell equipped aircraft will be returned to service promptly and economically This service is available both during and after warranty The aircraft owner operator is required to ensure that units provided through this program have been approved in accordance with their specific maintenance requirements All articles are returned to Reconditioned Specifications limits when they are processed through a Honeywell repair facility All articles are inspected by quality control personnel to verify proper w
129. rline A28 1146 102 03 Normal Operation REV3 4 5 PRIMUS 88U Digital Weather Radar system Radar Mode Ground Mapping NOTE Refer to Tilt Management in Section 5 Radar Facts for additional information on the use of tilt control Ground mapping operation is selected by setting the controls to GMAP The TILT control is turned down until a usable amount of navigable terrain is displayed The degree of down tilt depends on the aircraft altitude and the selected range The receiver STC characteristics are altered to equalize ground target reflection versus range As a result selecting preset GAIN generally creates the desired mapping display However the pilotcan controlthe gain manually by selecting manual gain and rotating the GAIN control to help achieve an optimum display With experience the pilot can interpret the color display patterns that indicate water regions coastlines hilly or mountainous regions cities or even large structures A good learning method is to practice ground mapping during flights in clear visibility where the radar dis play can be visually compared with the terrain TEST MODE The PRIMUS 880 Digital WeatherRadarS ystem has a self testmode and a maintenance function In the self test TST mode a special test pattern is displayed as illustrated earlier in this section The functions of this pattern are as follows e Color Bands A series of green yellow red magenta white bands indicat
130. rm detected at long range can appear to become weaker and actually disappearas itis approached This occurs because the storm cell which was fully within the beam at 100 NM gradually passes out of and under the radar beam When flying at low altitudes rotate tilt upward frequently to avoid flying under a thunderstorm There is some evidence that maximum turbulence exists at middle heights in storms 20 000 to 30 000 ft however turbulence beneath a storm is not to be minimized However the lower altitude may be affected by strong outflow winds and severe turbulence where thunderstorms are present The same turbulence considerations that oth to Het altitude flight near storms apply to low altitude flight Avoid all rapidly moving echoes by 20 miles A single thunderstorm echo a line of echoes ora cluster of echoes moving 40 knots or more will often contain severe weather Although nearby slower moving echoes may contain more intense aviation hazards all rapidly moving echoes warrant close observation Fast moving broken to solid line echoes are particularly disruptive to aircraft operations Avoid the entire cell if any portion of the cell is red or magenta by 20 NM The stronger the radar return the greater the frequency and severity of turbulence and hail Severe Weather Avoidance Procedures Table 5 12 cont A28 1146 102 00 Radar Facts 5 57 PRIMUS 88U Digital Weather Radar system Procedure Avoid all rapi
131. rovides no assurance of avoidance turbulence The radar scope also does not provide assurance of avoiding instrument weather from clouds and fog Your scope may be clear between intense echoes this clear does not mean you can fly Remember that while hail always gives a radar echo it may fall several miles from the nearest cloud and hazardous turbulence may extend to as muchas 20 miles from the echo edge Avoid intense or extreme level echoes by atleast 20 miles that is such echoes should be separated by atleast 40 miles before you fly between them With weaker echoes you can reduce the distance by which you avoid them DO S AND DON TS OF THUNDERSTORM FLYING Above all remember this Never regard any thunderstorm lightly even when radar observers reportthe echoes are of lightintensity Avoiding thunderstorms is the best policy Following are some do s and don ts of thunderstorm avoidance e Don t land or take off in the face of an approaching thunderstorm A sudden gust front of low level turbulence could cause loss of control e Don t attempt to fly under a thunderstorm even if you can see through to the other side Turbulence and wind shear under the storm could be disastrous e Dont fly without airborne radar into a cloud mass containing scattered embedded thunderstorms Scattered thunderstorms not embedded usually can be visually circumnavigated e Don t trust the visual appearance to be a reliable indicator of the turbulence
132. s ice crystals and above this level at lower temperatures the amount of supercooled water decreases e Supercooled water freezes on impact with an aircraft Clear icing can occur atany altitude above the freezing level butathigh levels icing from smaller droplets may be rime or mixed with rime and clear The abundance of large supercooled droplets makes clear icing very rapid between O C and 15 C and encounters can be frequent in a cluster of cells Thunderstorm icing can be extremely hazardous MOTION OF STORM DRY AIR INFLOW AW ANN A WARM AIR INFLOW Ohiri INS por WARM AIR INFLOW WAKE uM re L EM IN AIR A e OUTFLOW 10 5 NAUTICAL MILE 0 AD 37561 Schematic Cross Section of a Thunderstorm Figure A 1 Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 A 6 PRIMUS 88U Digital Weather Kadar system HAIL e Hail competes with turbulence as the greatest thunderstorm hazard to aircraft Supercooled drops above the freezing level begin to freeze Once a drop has frozen other drops latch on and freeze to it so the hailstone grows sometimes into a huge iceball Large hail occurs with severe thunderstorms with strong updrafts that have builtto greatheights Eventually the hailstones fall possibly some distance from the storm core Hail may be encountered in clear air several miles from dark thunderstorm clouds e As hailstones fallthrough air whose temperature is abov
133. s which do not contain vertical velocities as strong as those from storms overthe U S plains Then itis a matter of the pilot being informed with respect to the general atmospheric conditions accompanying storms for it is well known that PRACTICALLY ALL GEOGRAPHIC AREAS HAVING THUNDERSTORMS ARE OCCASIONALLY VISITED BY SEVERE ONES USE OF AIRBORNE RADAR Airborne radar is a valuable tool HOWEVER ITS USE IS PRINCIPALLY AS AN INDICATOR OF STORM LOCATIONS FOR AVOIDANCE PURPOSES WHILE ENROUTE Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 A 14 PRIMUS 9880 Digital Weather Radar System Appendix B Enhanced Ground Proximity Warning System EGPWS The Mark VII EGPWS combines information from aircraft navigation equipment i e flight management system FMS inertial reference system IRS global positioning system GPS radio altimeter with a stored terrain database that alerts the pilot to potentially dangerous ground proximity In addition to the verbal alert the EGPWS can display the terrain data on the weather radar indicator Depending on the installation the pilot pushes a button to display the terrain or the terrain data is automatically displayed when a Terrain Alert occurs SYSTEM OPERATION To display the EGPWS the weather system can be in any mode except OFF When the EGPWS is active the indicator range up and down arrows control the EGPWS display range The AZ button on the indicator is
134. sentradar returns When flying above the freezing level hailcan be expected in regions above and around wet storm cells found at lower altitudes The hail is carried up to the tropopause by strong vertical winds inside the storm In large storms these winds can easily exceed 200 kt making them very dangerous Since the core of such a storm is very turbulent but largely icy the red core on the radar display is weak or absent and highly mobile The storm core can be expected to change shapes with each antenna scan Radar Facts A28 1146 102 00 5 48 PRIMUS 88U Digital Weather Radar system Onreaching the tropopause the hail is ejected from the storm and falls downward to a point where it is sucked back into the storm When the hail falls below the freezing level however it begins to melt and form a thin surface layer of liquid detectable by radar A slight downward tilt of the antenna toward the warmer air shows rain coming from unseen dry hail thatis directly in the flightpath as shown in figure 5 36 At lower altitudes the reverse is sometimes true the radar may be scanning below a rapidly developing storm cell from which the heavy rain droplets have not had time to fall through the updrafts to the flight level Tilting the antenna up and down regularly produces the total weather picture Using a tilt setting that has the radar look into the area of maximum reflectivity 5000 to 20 000 ft gives the strongest radar picture Howeve
135. ssed below AVOID HOOK ECHOES BY 20 MILES The hook is probably the best known echo associated with severe weather Itis an appendage of a thunderstorm echo and usually only appears on weather radars Figure 5 42 shows a hook echo Radar Facts A28 1146 102 00 5 60 PRIMUS 88U Digital Weather Radar system AD 15560 R19 Typical Hook Pattern Figure 5 42 The hooks are located atthe right rear side of the thunderstorm echo s direction of movement usually the southwest quadrant The hook is not the tornado echo A small scale low pressure area is centered at the right rear side of the thunderstorm echo near its edge The low usually ranges from about 3 to 10 miles in diameter Precipitation is drawn around the low s cyclonic circulation to form the characteristic hook shape Tornadoes form within the low near hook According to statistics from the NSSL almost60 percentof allobserved hook echoes have tornadoes associated with them A tornado is always suspected when a hook echo is seen A hook can form with no tornadoes and vice versa However when a bona fide hook is observed on a weather radar moderate or greater turbulence strong shifting surface winds and hail are often nearby and aircraft should avoid them A28 1146 102 00 Radar Facts 5 61 PRIMUS 88U Digital Weather Radar system There are many patterns on radar that resemble hook echoes but are not associated with severe weather Severe weather hook echoes
136. t short bursts of electromagnetic energy that travel through space as a radio wave When the traveling wave of energy strikes a target some ofthe energy reflects back to the radar receiver Electronic circuits measure the elapsedtime between the transmission and the reception of the echo to determine the distance to the target range Because the antenna beam is scanning right and left in synchronism with the sectoring sweep on the indicator the bearing of the target is found as shown in figure 5 1 The indicator with the radar is called a plan position indicator PPI type When an architect makes a drawing for a house one ofthe views he generally shows is a plan view a diagram of the house as viewed from above The PPI aboard an airplane presents a cross sectional picture of the storm as though viewed from above In short itis NOT a horizon view of the storm cells ahead but rather a MAP view This positional relationship of the airplane and the storm cells as displayed by the indicator is shown in figure 5 1 A28 1146 102 00 Radar Facts 5 1 PRIMUS 88U Digital Weather Radar system AIRCRAFT HEADING 0 AD 12055 R2 Positional Relationship of an Airplane and Storm Cells Ahead as Displayed on Indicator Figure 5 1 The drawing is laid out to simulate the face of the indicator with the semicircular range marks To derive a clearer conceptofthe picture that the indicator presents imagine that the storm is a loaf o
137. t which the cyan field starts is approximately 290 with a 12 inch antenna For the 18 and 24 inch antennas the cyan field starts beyond 300 NM and therefore will not be seen if there are no intervening targets The RCT feature includes attenuation compensation Refer to Section 5 Radar Facts of this guide for a description of attenuation compensation Rainfall causes attenuation and attenuation compensation modifies the color calibration to maintain calibration regardless of the amount of attenuation Modifying the color calibration results in a change in the point where calibration can no longer keep the radar system calibrated for red level targets The heavier the rainfall the greater the attenuation and the shorter the range where XSTC runs out of control Therefore the range at which the cyan background starts varies depending on the amount of attenuation The greater the attenuation the closer the start of the cyan field The radar s calibration includes a nominal allowance for radome losses Excessive losses in the radome seriously affect radar calibration One possible means of verification are signal returns from known targets Honeywell recommends that the pilot report evidence of weak returns to ensure that radome performance is maintained at a level that does not affect radar calibration Target alert can be selected in any WX range The target alert circuit monitors for hazardous targets within 7 5 of the aircraft cente
138. the information on this page is subject to the restrictions on the title page of this document PRIMUS 9880 Digital Weather Radar System EGPWS Display The EGPWS displays is shown as variable dot patterns in green yellow or red The density and color is a function of how close the terrain is relative to the aircraft altitude above ground level AGL refer to table B 1 Terrain obstacle alerts are shown by painting the threatening terrain as solid or red Terrain that is more than 2000 feet below the aircraft is not displayed Areas where terrain data is not available are shown in magenta Elevation of Terrain in Feet AGL Color 2000 or more above the aircraft High density red 1000 2000 above the aircraft High density yellow dot pattern 0 1000 above the aircraft Medium Density yellow Dot Pattern 0 1000 below the aircraft Medium density green dot pattern 1000 2000 below the aircraft Low density green dot pattern 2000 or more below the aircraft black NOTE Caution terrain 60 second warning is displayed as solid yellow Warning obstacle 30 second warning is displayed as solid red EGPWS Obstacle Display Color Definitions Table B 1 Enhanced Ground Proximity Warning System EGPWS A28 1146 102 01 B 4 REV 1 PRIMUS 9880 Digital Weather Radar System Figure B 1 shows the EGPWS over KPHX airport at 2000 feet mean sea level heading north The terrain shows the mountains to the north of Phoenix AD 62964
139. the winds outside the storm to flow around the storm instead of carrying it along This also happens in wake eddies that often form downstream of the blocking updraft Interaction With Other Storms A thunderstorm that is located between another storm and its moisture source may cause the blocked storm to have erratic motion Sometimes the blocking of moisture is effective enough to cause the thunderstorm to dissipate Severe Weather Avoidance Procedures Table 5 12 cont Radar Facts A28 1146 102 00 5 58 PRIMUS 88U Digital Weather Radar system Step Procedure Three of the most common erratic motions are 1 Right Turning Echo This is the most frequently observed erratic motion Sometimes a thunderstorm echo traveling the same direction and speed as nearby thunderstorm echoes slows and turns to the right of its previous motion The erratic motion may lastan hour or more before it resumes its previous motion The storm should be considered severe while this erratic motion is in progress Splitting Echoes Sometimes a large 20 mile or larger diameter echo splits into two echoes The southernmost echo often slows turns to the right of its previous motion and becomes severe with large hail and extreme turbulence If a tornado develops it is usually at the right rear portion ofthe southern echo When the storm weakens it usually resumes its original direction of movement The northern echo moves left of the m
140. this action the pilot detects a changing dynamic error in aircraft attitude and corrects it Asthe gustlifts the wing the aircraftattitude source sends a continuous stream of attitude change information to stabilization circuits which in turn control the motors that raise and lower the beam In short a dynamic error in aircraftattitude as seen by the radar is detected and the antenna attitude is corrected for it Extremely small errors of less than 1 can be detected and compensated However the point is ultimately reached where dynamic error is too small to be detected Without detection there is no compensation Accelerative Error One of the most common forms of error seen in a radar antenna stabilization system results from forces of acceleration on the aircraft equipped with a vertical gyroscope Acceleration forces result from speeding up slowing down or turning Radar stabilization accuracy depends upon the aircraft vertical gyroscope Therefore any gyroscopic errors accumulated through acceleration are automatically imparted to the antenna stabilization system A vertical gyroscope contains a gravity sensitive element a heavily dampened pendulous device that enables the gyro to erect itselfto earth gravity atthe rate of approximately 2 min The pendulous device is unable to differentiate between earth gravity and an acceleration force It tends to rest at a false gravity position where the forces of gravity and accele
141. tion magenta REACT is available in the WX mode only and selecting REACT forces the system to preset gain When engaged the white RCT legend is displayed in the REACT field NOTES 1 REACT S three main functions attenuation compensation cyan field and forcing targets to magenta are switched on and off with the RCT switch 2 Refer to Section 5 Radar Facts for a description of REACT s STB Stabilization The STB button toggles pitch and roll stabilization ON and OFF Itis also used with the STB adjust mode and to override forced standby The radar antenna is normally attitude stabilized It automatically compensates for roll and pitch maneuvers refer to Section 5 Radar Facts for a description of stabilization The STB OFF annunciator is displayed on the screen A28 1146 102 00 Operating Controls 3 7 PRIMUS 9880 Digital Weather Radar System The radar antenna is normally attitude stabilized It automatically compensates for roll and pitch maneuvers refer to Section 5 Radar Facts for a description of stabilization The STB OFF annunciator is displayed on the screen 6 TRB Turbulence The TRB switch is used to select the turbulence detection mode of operation The TRB mode can only be selected if the FUNCTION switch is in the WX position and the selected range is 50 miles or less The weather turbulence mode is annunciated in the mode field with the WX T legend Areas of moderate or greater turbulence are show
142. torms are present Therefore THE SAME TURBULENCE CONSIDERATIONS WHICH APPLY TO FLIGHT AT HIGH ALTITUDES NEAR STORMS APPLY TO LOW LEVELS AS WELL Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 A 12 PRIMUS 88U Digital Weather Radar system MAXIMUM STORM TOPS Photographic data indicates that the maximum height attained by thunderstorm clouds is approximately 63 000 feet Such very tallstorm tops have not been explored by direct means but meteorological judgments indicate the probable existence of large hail and strong vertical drafts to within a few thousand feet ofthe top of these isolated stratosphere penetrating storms THEREFORE IT APPEARS IMPORTANT TO AVOID SUCH VERY TALL STORMS AT ALL ALTITUDES HAIL IN THUNDERSTORMS The occurrence of HAIL IS MUCH MORE CLEARLY IDENTIFIED WITH THE INTENSITY OF ECHOES THAN IS TURBULENCE AVOIDANCE OF MODERATE AND SEVERE STORMS SHOULD ALWAYS BE ASSOCIATED WITH THE AVOIDANCE OF DAMAGING HAIL VISUAL APPEARANCE OF STORM AND ASSOCIATED TURBULENCE WITH THEM On numerous occasions flight at NSSL have indicated that NO USEFUL CORRELATION EXISTS BETWEEN THE EXTERNAL VISUAL APPEARANCE OF THUNDERSTORMS AND THE TURBULENCE AND HAIL WITHIN THEM MODIFICATION OF CRITERIA WHEN SEVERE STORMS AND RAPID DEVELOPMENT ARE EVIDENT During severe storm situations radar echo intensities may grow by a factor of ten each minute and cloud tops by 7 000 feet per minute THEREFORE NO F
143. ts the least reflective return yellow is a moderate return and magenta is a strong return If GMAP is selected before the initial RTA warmup period is complete a flashing WAIT legend is displayed In WAIT mode the transmitter and antenna scan are inhibited and the memory is erased When the warmup is complete the system automatically switches to the GMAP mode WARNING THE SYSTEM PERFORMS ONLY THE FUNCTIONS OF WEATHER DETECTION OR GROUND MAPPING IT CANNOT BE RELIED UPON FOR PROXIMITY WARNING OR ANTICOLLISION PROTECTION e FSBY Forced standby is an automatic nonselectable radar mode Asaninstallation option the controllers can be wired to the WOW squat switch When wired the RTA is in the forced standby mode when the aircraft is on the ground In the forced standby mode the transmitter and antenna scan are both inhibited the memory is erased and the amber FSBY legend is displayed in the mode field When in the forced standby mode pushing the STAB button 4 times in 3 seconds exits the mode FSBY mode is a safety feature that inhibits the transmitter on the ground to eliminate the X band microwave radiation hazard R efer to Section 6 Maximum P ermissible Exposure Level MPEL NOTE In dual installations overriding the forced standby using the TGT button is done on only one controller WARNING FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERATOR TO ENSURE SAFETY FOR GROUND PERSONNEL GAIN The GAIN is a singl
144. turbulence 3 8 PRIMUS 880 power up procedure 4 2 roll gain adjustment 5 29 severe weather avoidance procedures 5 60 stabilization in straight and level flight check procedure 5 21 stabilization in turns check procedure 5 23 P Pitch and roll trim adjustments 5 19 Preliminary control settings 4 1 Radar mode ground mapping 4 6 power up procedure 4 1 radar mode weather 4 4 standby 4 4 Procedures in flight roll offset adjustment procedure 5 26 pitch gain adjustment 5 30 pitch offset adjustment procedure 5 28 A28 1146 102 01 REV 1 R Radar facts additional comments 5 68 turbulence versus distance from storm core 5 68 turbulence versus distance from storm edge 5 68 configurations of individual echoes Northern Hemisphere 5 60 avoid all crescent shaped echoes by 20 miles 5 64 avoid hook echoes by 20 miles 5 60 avoid pendant by 20 miles 5 63 avoid steep rain gradients by 20 miles 5 64 avoid V notch by 20 miles 5 62 ground mapping 5 69 interpreting weather radar images 5 31 line configurations 5 65 avoid bow shaped line of echoes by 20 miles 5 67 avoid line echo wave patterns LEWP by 20 miles 5 66 avoid thunderstorm echoes at the south end of a line or at a break in a line by 20 miles 5 65 radar operation 5 1 radome 5 54 Index Index 3 PRIMUS 9880 Digital Weather Radar System Index cont Radar facts cont rain echo attenuation compensation techni
145. utomatic pilot disengage altitude hold mode and speed hold mode The automatic altitude and airspeed controls will increase maneuvers ofthe aircraftthus increasing structuralstress e f using airborne radar tilt the antenna up and down occasionally This will permit you to detectother thunderstorm activity ataltitudes other than the one being flown Following are some do s and don ts during thunderstorm penetration e Dokeepyoureyes on your instruments Looking outside the cockpit can increase danger of temporary blindness from lightning e Dont change power settings maintain settings for the recommended turbulence penetration airspeed e Do maintain constant attitude let the aircraft ride the waves Maneuvers in trying to maintain constantaltitude increase stress on the aircraft e Don t turn back once you are in a thunderstorm A straight course through the storm most likely will get you out of the hazards most quickly In addition turning maneuvers increase stress on the aircraft Federal Aviation Administration FAA Advisory Circulars A28 1146 102 00 A 10 PRIMUS 88U Digital Weather Radar system National Severe Storms Laboratory NSSL Thunderstorm Research The NSSL has since 1964 been the focal point of our thunderstorm research In flight conditions obtained from thunderstorm penetration by controlled especially equipped high performance aircraft are compared by the NSSL with National Weather Service NWS ty
146. y of the Universal Digital Interface UDI connector These systems have priority for access to the radar display screen These systems data may be overlaid on the EGPWS display or they may simply override the EGPWS display EGPWS Operation The EGPWS system may vary depending on the installed controls and software level of the EGPWS computer In some installations the EGPWS display on the radar indicator is manually operated It is only displayed if the pilot pushes the ON button and it is removed if the pilot pushes the ON button a second time In some installations the EGPWS display has a pop up mode in which the terrain display is automatically displayed when the EGPWS system detects a terrain alert situation The pilot can remove the ground display from the radar indicator or prevent the EGPWS system from displaying ground on the radar indicator by pushing the INHIB button The 1 and range buttons on the radar indicator control the range of the ground display The radar indicator AZ button is active and can display or remove azimuth buttons The other radar controls do not change the ground display but if they are used while EGPWS is displayed they control the radar RTA and the effects of any changes are seen when the radar image is re displayed For additional information refer to the appropriate EGPWS operating manual A28 1146 102 03 Enhanced Ground Proximity Warning System EGPWS REV 3 B 3 Use or disclosure of

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