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Aircraft compass systems misaligned while taxiing. Flight crew realigned platforms. Allegedly this is a continuing problem.
| Attributes | |
| ACN | 130051 |
| Time | |
| Date | 198911 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : dfw |
| State Reference | TX |
| Altitude | agl bound lower : 0 agl bound upper : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : cvg |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | ground other : taxi |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : flight engineer pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 6300 flight time type : 325 |
| ASRS Report | 130051 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
While on parallel taxiway for 36R dfw, aircraft ahrs compass systems oscillated +/-20 degrees, left and right systems. On end of runway platforms were realigned and heading monitor annunciations were cleared. This has been a persistent problem with this model of the medium large transport. Callback conversation with reporter revealed the following: this is a poor compass system. It is affected at several locations: atl, stl, dfw, etc. We also have 2 instances of the compass heading reading 60 degrees off the proper heading. 1 flight crew reportedly has been violated for the track deviation because of the erroneous heading displayed. It is such a bad system it is predictable at some locations that the headings will split or oscillate. It is common knowledge among the pilots that when the aircraft is on the autoplt in flight, that it will oscillate left-right turns as though the yaw damper had failed. Company is aware of problem--union safety reps pursuing a solution.
Original NASA ASRS Text
Title: ACFT COMPASS SYSTEMS MISALIGNED WHILE TAXIING. FLT CREW REALIGNED PLATFORMS. ALLEGEDLY THIS IS A CONTINUING PROBLEM.
Narrative: WHILE ON PARALLEL TXWY FOR 36R DFW, ACFT AHRS COMPASS SYSTEMS OSCILLATED +/-20 DEGS, LEFT AND RIGHT SYSTEMS. ON END OF RWY PLATFORMS WERE REALIGNED AND HDG MONITOR ANNUNCIATIONS WERE CLRED. THIS HAS BEEN A PERSISTENT PROB WITH THIS MODEL OF THE MLG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THIS IS A POOR COMPASS SYS. IT IS AFFECTED AT SEVERAL LOCATIONS: ATL, STL, DFW, ETC. WE ALSO HAVE 2 INSTANCES OF THE COMPASS HDG READING 60 DEGS OFF THE PROPER HDG. 1 FLT CREW REPORTEDLY HAS BEEN VIOLATED FOR THE TRACK DEVIATION BECAUSE OF THE ERRONEOUS HDG DISPLAYED. IT IS SUCH A BAD SYS IT IS PREDICTABLE AT SOME LOCATIONS THAT THE HDGS WILL SPLIT OR OSCILLATE. IT IS COMMON KNOWLEDGE AMONG THE PLTS THAT WHEN THE ACFT IS ON THE AUTOPLT IN FLT, THAT IT WILL OSCILLATE LEFT-RIGHT TURNS AS THOUGH THE YAW DAMPER HAD FAILED. COMPANY IS AWARE OF PROB--UNION SAFETY REPS PURSUING A SOLUTION.
Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.