# JASC 3444: Ground Proximity System

- Type: JASC system/component code (FAA)
- ATA chapter: 34 Navigation
- Title in the code table: GROUND PROXIMITY SYSTEM
- Service difficulty reports: 553
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=40
- Page: https://openairdocs.org/jasc/3444

## What it covers

The system which detects and alerts flight crew to potential terrain hazards. Includes the antenna which transmits and receives an electronic signal for the radio altimeter equipment used for terrain-to-aircraft distance. Also includes the component which interprets a radio signal reflected back to a receiver to determine distance from the nearest terrain; and the component which process the warning computer input signals from various sources in order to determine if and when the crew should be alerted of a terrain hazard.

## Service difficulty reports (553, newest 50)

- [SDR VNAA2026102326901](https://openairdocs.org/sdr/VNAA2026102326901), Oct 22, 2026: Cndair CL6002C10. ALTIMETER. FAULTED. GROUND SPOILER DEPLOY CAUTION ON APPROACH. REMOVED AND REINSTALLED RADAR ALT CONVERTERS. IAW AMM 34-44-04-400-801-A02-PS (N703PS)
- [SDR HNAA2026092900916](https://openairdocs.org/sdr/HNAA2026092900916), Sep 29, 2026: Emb EMB145LR. COMPUTER. ABNORMAL. BURNING SMELL ONLY IN COCKPIT AND C/B J8 GPWS POPPED. FACT 29SEP26 11:32 BDL R&R GPWS COMPUTER IRW EMB-145 AMM 24-41-01. (N682AE)
- [SDR HNAA2026092900716](https://openairdocs.org/sdr/HNAA2026092900716), Sep 29, 2026: Emb EMB145LR. COMPUTER. ABNORMAL. BURNING SMELL ONLY IN COCKPIT AND C/B J8 GPWS POPPED. FACT 29SEP26 11:32 BDL RAR GPWS COMPUTER IRW EMB-145 AMM 24-41-01. (N682AE)
- [SDR AALA202609281422](https://openairdocs.org/sdr/AALA202609281422), Sep 27, 2026: Boeing 7878. ALTIMETER. FAULT MESSAGE. AIRCRAFT WAS NOT GROUNDED: SHORTLY AFTER TAKE OFF RADIO ALTIMETER LT & RT MESSAGE ALONG WITH AUTO THROTTLE DISC MESSAGE. (N877BF)
- [SDR A6WA202609028911](https://openairdocs.org/sdr/A6WA202609028911), Sep 2, 2026: Cndair CL6002B19. ALTIMETER. MALFUNCTIONED. ON TAKE OFF RADAR ALT ACTING ERRATIC, SETTING OFF TERRAIN GPWS WARNING. ABOVE 2500' RAD ALT CLEARED OFF OF PFD. RETURNED (N442AW)
- [SDR A6WA202608198908](https://openairdocs.org/sdr/A6WA202608198908), Aug 19, 2026: Cndair CL6002B19. ANTENNA. FAULTED. ON T/O, RADAR ALTIMETER MALFUNCTIONED READING 1000FT WHILE A/C WAS CLIMBING 2200 AGL RECEIVED TERRAIN GPWS AURAL ON APPR (N444ZW)
- [SDR DALA2026081904728](https://openairdocs.org/sdr/DALA2026081904728), Aug 13, 2026: Boeing 717200. TRANSMITTER. FAULTED. CORROSION UNDER THE NR 2 RADIO ALTIMETER TRANSMITTER AT STA 569 BETWEEN L-29L AND L-30, CORRECTIVE ACTION: COMPLIED WITH (N966AT)
- [SDR N6WA2026073002](https://openairdocs.org/sdr/N6WA2026073002), Jul 30, 2026: Cndair CL6002C11. RADIO ALTIMETER. FAULTED. GLD UNSAFE CAUTION MESSAGE. RERACKED RADIO ALT TRANSCEIVERS 1 AND 2 IAW AMM 34-44-01 CLEANED RAD ALT ANTENNAS AND PERFOR (N578GJ)
- [SDR QR9R2026072700001](https://openairdocs.org/sdr/QR9R2026072700001), Jul 27, 2026: Bolkms BK117C2. ALTIMETER. INOPERATIVE. DURING RUN-UP, RADAR ALTIMETER FOUND TO BE INOPERATIVE READING 600' ON THE PAD. REMOVED AND REPLACED RADAR ALTIMETER IAW
- [SDR N6WA2026071506](https://openairdocs.org/sdr/N6WA2026071506), Jul 15, 2026: Cndair CL6002C11. ANTENNA. DIRTY. GLD USAFE CAUTION MESSAGE 65 KIAS LOW ENERGY.( MOMENTARILY.) CLEANED ANTENNAS AND PREFORMED OPS TEST OF RADAR ALTIMETER  (N578GJ)
- [SDR DALA2026071304091](https://openairdocs.org/sdr/DALA2026071304091), Jul 10, 2026: Boeing 717200. TRANSCEIVER. FAULTY. ATB- RETURNED TO DTW DUE TO MULTIPLE FAULTS AFTER GEAR RETRACTION. REPLACED ALL RADIO ALTIMETER ANTENNAS AND BOTH TRANSC (N934AT)
- [SDR ABXA20260617264](https://openairdocs.org/sdr/ABXA20260617264), Jun 17, 2026: Boeing 767338. RADAR. FAULTED. DURING TAXI, CREW RECEIVED NO LAND 3 AND C RAD ALT INDICATION. RETURNED TO THE GATE (BTB). MTC DEFERRED RAD ALT PER MEL  (N371CM)
- [SDR CALA2026061517084](https://openairdocs.org/sdr/CALA2026061517084), Jun 12, 2026: Boeing 7379. CONTROL SWITCH. FAULTED. TOO LOW GEAR AURAL NO FAULT ON AHM, NO EXISTING ON CH34. BITE TEST PSEU AND LGTV ALL PASSED. DEBRIEFED CREW ON ARRIVAL.  (N17405)
- [SDR ABXA20260528231](https://openairdocs.org/sdr/ABXA20260528231), May 28, 2026: Boeing 767232. ANTENNA. DEFECTIVE. WHILE DESCENDING THRU FL 280 AND BELOW, GEAR NOT DOWN EICAS WARNING AND CONFIG LIGHT CAME ON WHEN THRUST LEVERS ARE AT I (N745AX)
- [SDR ABXA20260410158](https://openairdocs.org/sdr/ABXA20260410158), Apr 10, 2026: Boeing 767306. RADIO ALTIMETER. FAULTED. DURING APPROACH, GEAR NOT DOWN EICAS WARNING RECIEVED AT FL190 DESCENDING AT IDLE THRUST ON ARRIVAL. DEFERRED L RAD ALT  (N1427A)
- [SDR DALA2026040602167](https://openairdocs.org/sdr/DALA2026040602167), Apr 2, 2026: Airbus A330323. COMPUTER. FAULTED. ATO- DUE TO (NAV GPWS) FAULT AT THROTTLE UP. PLACED GPWS ON MEL. THEN REPLACED T2CAS COMPUTER ON ARRIVAL IN LAX. OK FOR  (N806NW)
- [SDR ABXA20260327134](https://openairdocs.org/sdr/ABXA20260327134), Mar 27, 2026: Boeing 76731B. RADIO ALTIMETER. FAULTED. DURING DESCENT, GEAR NOT DOWN RED EICAS MESSAGE CAME ON AROUND 5000FT ON THE ARRIVAL WITH FLAPS SET AT 1 SEVERAL TIMES W (N1361A)
- [SDR AALA202511246100](https://openairdocs.org/sdr/AALA202511246100), Nov 22, 2025: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: IN FLIGHT WITH SPEED BRAKES DEPLOYED, LANDING GEAR HORN SOUNDED IN CONJUNCTION WITH THREE RED LAN (N987NN)
- [SDR AALA202511244860](https://openairdocs.org/sdr/AALA202511244860), Nov 22, 2025: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: IN FLIGHT WITH SPEED BRAKES DEPLOYED, LANDING GEAR HORN SOUNDED IN CONJUNCTION WITH THREE RED LAN (N987NN)
- [SDR AALA202511246336](https://openairdocs.org/sdr/AALA202511246336), Nov 22, 2025: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: IN FLIGHT WITH SPEED BRAKES DEPLOYED, LANDING GEAR HORN SOUNDED IN CONJUNCTION WITH THREE RED LAN (N987NN)
- [SDR AALA202511246778](https://openairdocs.org/sdr/AALA202511246778), Nov 22, 2025: Boeing 737823. ANTENNA. FAULTY. AIRCRAFT WAS GROUNDED: IN FLIGHT WITH SPEED BRAKES DEPLOYED, LANDING GEAR HORN SOUNDED IN CONJUNCTION WITH THREE RED LAN (N987NN)
- [SDR AALA202511179177](https://openairdocs.org/sdr/AALA202511179177), Nov 15, 2025: Boeing 737823. ANTENNA. FALSE INDICATION. AIRCRAFT WAS NOT GROUNDED: AT 6000 FT WITH GEAR AND FLAPS UP GEAR WARNING HORN SOUNDED FOR APPROXIMATELY 2 SECONDS WITH  (N843NN)
- [SDR AALA202511170218](https://openairdocs.org/sdr/AALA202511170218), Nov 15, 2025: Boeing 737823. ANTENNA. FALSE INDICATION. AIRCRAFT WAS NOT GROUNDED: AT 6000 FT WITH GEAR AND FLAPS UP GEAR WARNING HORN SOUNDED FOR APPROXIMATELY 2 SECONDS WITH  (N843NN)
- [SDR AALA202511170938](https://openairdocs.org/sdr/AALA202511170938), Nov 15, 2025: Boeing 737823. ANTENNA. FALSE INDICATION. AIRCRAFT WAS NOT GROUNDED: AT 6000 FT WITH GEAR AND FLAPS UP GEAR WARNING HORN SOUNDED FOR APPROXIMATELY 2 SECONDS WITH  (N843NN)
- [SDR AALA202511176584](https://openairdocs.org/sdr/AALA202511176584), Nov 15, 2025: Boeing 737823. ANTENNA. FALSE INDICATION. AIRCRAFT WAS NOT GROUNDED: AT 6000 FT WITH GEAR AND FLAPS UP GEAR WARNING HORN SOUNDED FOR APPROXIMATELY 2 SECONDS WITH  (N843NN)
- [SDR JJBA20251120097](https://openairdocs.org/sdr/JJBA20251120097), Nov 5, 2025: Emb EMB145XR. MOUNT. CORRODED. RADIO ALTIMETER (RAR 2) MOUNT HAS CORROSION/PITTING ON CONNECTOR HOLE LOWER EDGE. INSTALLED COMPLETE RADIO ALTIMETER (RA (N12195)
- [SDR QXEA2025102400328](https://openairdocs.org/sdr/QXEA2025102400328), Oct 21, 2025: Emb ERJ170200LR. ANTENNA. MALFUNCTIONED. FLIGHT 2106. AFTER TAKEOFF AT ABOUT 400 AGL RECIEVED GND PROX WARNING. WHEN SELECTING FLAPS 0, LANDING GEAR AURAL WARNIN (N628QX)
- [SDR AALA202510068236](https://openairdocs.org/sdr/AALA202510068236), Oct 4, 2025: Boeing 7378. TRANSCEIVER. FALSE INDICATION. AIRCRAFT WAS NOT GROUNDED: GEAR WARNING HORN SOUNDED FOR APPROXIMATELY 60-SECONDS DURING THE DESCENT AT 240 KNOTS WITH G (N318TD)
- [SDR QR9R2025100200002](https://openairdocs.org/sdr/QR9R2025100200002), Oct 2, 2025: Bolkms BK117C2. ALTIMETER. INOPERATIVE. RADAR ALTIMETER INOP DURING START RUNUP. REMOVED AND REPLACED RADAR ALTIMETER IAW NAV/COM 23-41-01; MOC SUCCESSFULLY COM
- [SDR VNAA2025090211101](https://openairdocs.org/sdr/VNAA2025090211101), Aug 29, 2025: Cndair CL6002C10. TRANSCEIVER. FLUCTUATES. IN-FLIGHT AT FL20.0 WE EXPERIENCED THE RA START TO MAKE 25.00FT, 500FT, 100FT CALL OUTS AND FLUCTUATE. / REMOVED AND REP (N542EA)
- [SDR DALA2025081906202](https://openairdocs.org/sdr/DALA2025081906202), Aug 18, 2025: Boeing 757251. TRANSCEIVER. INOPERATIVE. -MISC/DE- DUE TO GEAR NOT DOWN GPWS WARNING. REPLACED LEFT RADIO ALTIMETER TRANSCEIVER. (N552NW)
- [SDR AALA202508015708](https://openairdocs.org/sdr/AALA202508015708), Jul 30, 2025: Boeing 7879. GPS. MALFUNCTIONED. AIRCRAFT WAS NOT GROUNDED: GPS GOT JAMMED IN GEORGA AND DID NOT COME BACK. BURNED TO MUCH FUEL AS A RESULT AND MADE A FU (N823AN)
- [SDR DALA2025072005441](https://openairdocs.org/sdr/DALA2025072005441), Jul 19, 2025: Boeing 717200. TRANSCEIVER. FAULTED. SHIP 9523-ATO- ABORTED TAKE-OFF DUE TO RECEIVING A STICK PUSHER FAIL MESSAGE. CORRECTIVE ACTION: MAINTENANCE REPLACED BO (N964AT)
- [SDR DALA2025052704093](https://openairdocs.org/sdr/DALA2025052704093), May 27, 2025: Airbus A319114. RADIO ALTIMETER. FAULTED. SHIP 3145 - ATB - DUE TO AURAL WARNING "RETARD" WITH NAV RA 2 FAULT ECAM WARNING. CORRECTIVE ACTION: REPLACED RADIO ALTI (N345NB)
- [SDR AALA202504049130](https://openairdocs.org/sdr/AALA202504049130), Apr 3, 2025: Boeing 737823. GPWS. FAULTED. AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS NOT DECLARED DUE TO: TERRIAN FAILED ON BOTH CAPTAIN AND FIRST OFFICER NAVIGA (N901NN)
- [SDR YENA2025020500134](https://openairdocs.org/sdr/YENA2025020500134), Feb 2, 2025: Airbus BD5001A11. RADAR. FAULTED. FLT#125, JFK-TPA. (AIRCRAFT DIVERTED TO RDU) GPWS TERRAIN WARNING AT FL340 THROUGH DESCENT ( TERRAIN AWARENESS AND WARNI (N3240J)
- [SDR YENA2025012700106](https://openairdocs.org/sdr/YENA2025012700106), Jan 22, 2025: Airbus BD5001A11. TRANSCEIVER. FAULTED. FLT#1185, JFK- RDU. (AIRCRAFT PERFORMED AN AIR TURN BACK TO JFK) ' AFTER TAKEOFF, THE #2 RA WAS GIVING BAD INFO UP TP FL (N3102J)
- [SDR CWQA20250106220](https://openairdocs.org/sdr/CWQA20250106220), Dec 20, 2024: Cessna 680A. GSD. FAILED. DURING CRUISE CREW RECEIVED GSD FAIL #2 CAS MESSAGE (GARMIN DATA CONCENTRATOR UNIT),CHECKLIST REQUIRED USE OF EMERGENCY  (N304LH)
- [SDR QR9R2024091900002](https://openairdocs.org/sdr/QR9R2024091900002), Sep 19, 2024: Bolkms BK117C2. RADIO ALTIMETER. INOPERATIVE. ABORTED TAKEOFF. RADAR ALTIMETER INOP. DURING TROUBLESHOOTING, RADAR ALTIMETER WOULD NOT DISPLAY OR RESET. REMOVED AND R
- [SDR SIMA20240909001](https://openairdocs.org/sdr/SIMA20240909001), Sep 9, 2024: Emb ERJ170200LR. TRANSPONDER. FAILED. ON CLIMB OUT WE RECEIVED A "BANK ANGLE" AND "TOO LOW TERRAIN" CALL AT 1,000 AGL. ONCE THOSE MESSAGES CLEARED WE RECEIVED (N249NN)
- [SDR AALA202408281965](https://openairdocs.org/sdr/AALA202408281965), Aug 27, 2024: Boeing 737823. RADIO ALTIMETER. FAULTED. AIRCRAFT WAS GROUNDED: DESCENDING INTO MIA PASSING THROUGH APPROXIMATELY 10,000 FEET, THE LANDING GEAR CONFIGURATION WAR (N854NN)
- [SDR AALA202408073814](https://openairdocs.org/sdr/AALA202408073814), Aug 6, 2024: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: ON DESCENT AT APPROXIMATELY 7000 FEET AND 210 KNOTS LANDING GEAR WARNING HORN AND GEAR LIGHTS CAM (N962NN)
- [SDR AALA202408079690](https://openairdocs.org/sdr/AALA202408079690), Aug 6, 2024: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: ON DESCENT AT APPROXIMATELY 7000 FEET AND 210 KNOTS LANDING GEAR WARNING HORN AND GEAR LIGHTS CAM (N962NN)
- [SDR AALA202408070020](https://openairdocs.org/sdr/AALA202408070020), Aug 6, 2024: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: ON DESCENT AT APPROXIMATELY 7000 FEET AND 210 KNOTS LANDING GEAR WARNING HORN AND GEAR LIGHTS CAM (N962NN)
- [SDR AALA202408079265](https://openairdocs.org/sdr/AALA202408079265), Aug 6, 2024: Boeing 737823. ANTENNA. FAULTED. AIRCRAFT WAS GROUNDED: ON DESCENT AT APPROXIMATELY 7000 FEET AND 210 KNOTS LANDING GEAR WARNING HORN AND GEAR LIGHTS CAM (N962NN)
- [SDR SIMA20240616001](https://openairdocs.org/sdr/SIMA20240616001), Jun 16, 2024: Emb ERJ170100SE. RADAR. FAULTED. CAPT RADAR ALTIMETER INDICATED AT 5 FT ON CLIMB OUT. "LANDING GEAR" AURAL WARNING THROUGH ENTIRE ARRIVAL. AML PAGE 48554 (N651RW)
- [SDR YENA2024060300807](https://openairdocs.org/sdr/YENA2024060300807), Jun 1, 2024: Airbus A321271N. WARNING MESSAGE. FALSE ACTIVATION. FLT#1124, LAX-JFK. 'AT CRUISE ALT RA 2 FAULT ON ECAM; PERFORMED RA 2 TEST SYSTEM IAW AMM 34-42-00-730-050-C. TEST OK. NO (N2169J)
- [SDR UIEA2024051900393](https://openairdocs.org/sdr/UIEA2024051900393), May 18, 2024: Boeing 7673S1. WARNING MESSAGE. ILLUMINATED. IN-FLIGHT, WE HAD A GRD PROX SYS MSG. WE RAN THE QRH & THE MSG WENT AWAY. WHILE ON APPROACH, WE RECEIVED EGPWS PULL- (N640GT)
- [SDR SIMA20240428002](https://openairdocs.org/sdr/SIMA20240428002), Apr 28, 2024: Emb ERJ170100SE. RADAR. MALFUNCTIONED. RA-1 ISSUES DURING CLIMB OUT WAS DECREASING/RECEIVED PULL UP TERRAIN AURAL WARNING. RADAR ALT SYSTEM - 1 INOP - M1. REVE (N649RW)
- [SDR SIMA202404174001](https://openairdocs.org/sdr/SIMA202404174001), Apr 14, 2024: Emb ERJ170200LR. ANTENNA. FAILED. LANDING GEAR AURAL WARNING AT 10000 FT. / RADAR ALT 2 FAIL T/S RADAR ALTIMETER SYSTEM 2 IAW WM 34-31-51 AND PERFORMED OP (N285NN)

All 553: https://openairdocs.org/jasc/3444/reports.md

## Other codes in chapter 34

- [JASC 3400](https://openairdocs.org/jasc/3400): Navigation System (692 reports)
- [JASC 3410](https://openairdocs.org/jasc/3410): Flight Environment Data (218 reports)
- [JASC 3411](https://openairdocs.org/jasc/3411): Pitot/Static System (1,586 reports)
- [JASC 3412](https://openairdocs.org/jasc/3412): Outside Air Temperature Indicator/Sensor (254 reports)
- [JASC 3413](https://openairdocs.org/jasc/3413): Rate of Climb Indicator (157 reports)
- [JASC 3414](https://openairdocs.org/jasc/3414): Airspeed/Mach Indicator (860 reports)
- [JASC 3415](https://openairdocs.org/jasc/3415): High Speed Warning (39 reports)
- [JASC 3416](https://openairdocs.org/jasc/3416): Altimeter, Barometric/Encoder (1,256 reports)
- [JASC 3417](https://openairdocs.org/jasc/3417): Air Data Computer (1,211 reports)
- [JASC 3418](https://openairdocs.org/jasc/3418): Stall Warning System (1,641 reports)
- [JASC 3420](https://openairdocs.org/jasc/3420): Attitude and Direction Data System (772 reports)
- [JASC 3421](https://openairdocs.org/jasc/3421): Attitude Gyro and Indicating System (1,142 reports)
- [JASC 3422](https://openairdocs.org/jasc/3422): Directional Gyro and Indicating System (649 reports)
- [JASC 3423](https://openairdocs.org/jasc/3423): Magnetic Compass (101 reports)
- [JASC 3424](https://openairdocs.org/jasc/3424): Turn and Bank/Rate of Turn Indicator (153 reports)
- [JASC 3425](https://openairdocs.org/jasc/3425): Integrated Flight System (1,150 reports)
- [JASC 3430](https://openairdocs.org/jasc/3430): Landing and Taxi Aids (56 reports)
- [JASC 3431](https://openairdocs.org/jasc/3431): Localizer/VOR System (129 reports)
- [JASC 3432](https://openairdocs.org/jasc/3432): Glide Slope System (66 reports)
- [JASC 3433](https://openairdocs.org/jasc/3433): Microwave Landing System (26 reports)
- [JASC 3434](https://openairdocs.org/jasc/3434): Marker Beacon System (27 reports)
- [JASC 3435](https://openairdocs.org/jasc/3435): Heads Up Display System (10 reports)
- [JASC 3436](https://openairdocs.org/jasc/3436): Wind Shear Detection System (70 reports)
- [JASC 3440](https://openairdocs.org/jasc/3440): Independent Position Determining System (261 reports)
- [JASC 3441](https://openairdocs.org/jasc/3441): Inertial Guidance System (289 reports)
- [JASC 3442](https://openairdocs.org/jasc/3442): Weather Radar System (3,443 reports)
- [JASC 3443](https://openairdocs.org/jasc/3443): Doppler System (110 reports)
- [JASC 3445](https://openairdocs.org/jasc/3445): Air Collision Avoidance System (214 reports)
- [JASC 3446](https://openairdocs.org/jasc/3446): Non Radar Weather System (23 reports)
- [JASC 3450](https://openairdocs.org/jasc/3450): Dependent Position Determining System (106 reports)
- [JASC 3451](https://openairdocs.org/jasc/3451): DME/TACAN System (197 reports)
- [JASC 3452](https://openairdocs.org/jasc/3452): ATC Transponder System (624 reports)
- [JASC 3453](https://openairdocs.org/jasc/3453): Long-Range Navigation (LORAN) System (175 reports)
- [JASC 3454](https://openairdocs.org/jasc/3454): Visual Omnirange (VOR) System (317 reports)
- [JASC 3455](https://openairdocs.org/jasc/3455): Automatic Direction Finder (ADF) System (164 reports)
- [JASC 3456](https://openairdocs.org/jasc/3456): Omega Navigation System (9 reports)
- [JASC 3457](https://openairdocs.org/jasc/3457): Global Positioning System (635 reports)
- [JASC 3460](https://openairdocs.org/jasc/3460): Flight Management Computing Hardware System (4,690 reports)
- [JASC 3461](https://openairdocs.org/jasc/3461): Flight Management Computing Software System (68 reports)
- [JASC 3497](https://openairdocs.org/jasc/3497): Navigation System Wiring (269 reports)

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