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CRJ900 captain reports the FMS switching to true heading mode on its' own volition at FL360. The FMS is returned to magnetic.
| Attributes | |
| ACN | 954493 |
| Time | |
| Date | 201106 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | Regional Jet 900 (CRJ900) |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 1 Flight Crew Total 5000 Flight Crew Type 1000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe |
Narrative:
Level at 36;000 on a heading of south in the middle of the continent. I noticed the heading indicator move a few degrees all on its own. I then noted that my mfd displayed TRU1 and the first officers TRU2. We immediately realized the aircraft had gone into true heading mode all on it's own. We were captured in a navigation mode so there was no change in our actual heading. We reverted the FMS back into mag mode and continued without incident. The aircraft entered this mode all on its own without either of us engaging with the FMS.I felt it worth sharing that the aircraft entered this state without the influence of either myself or the first officer. As we were in mid continent our compass variation was minimal and since we were in navigation mode the aircraft never left proper course. It is worth bringing to the attention of other crews to be vigilant of the crjs automation as I have also experienced the speed mode changing from 250 knots to 40 knots without command from the crew.
Original NASA ASRS Text
Title: CRJ900 Captain reports the FMS switching to true heading mode on its' own volition at FL360. The FMS is returned to magnetic.
Narrative: Level at 36;000 on a heading of south in the middle of the continent. I noticed the heading indicator move a few degrees all on its own. I then noted that my MFD displayed TRU1 and the First Officers TRU2. We immediately realized the aircraft had gone into true heading mode all on it's own. We were captured in a NAV mode so there was no change in our actual heading. We reverted the FMS back into mag mode and continued without incident. The aircraft entered this mode all on its own without either of us engaging with the FMS.I felt it worth sharing that the aircraft entered this state without the influence of either myself or the First Officer. As we were in mid continent our compass variation was minimal and since we were in NAV mode the aircraft never left proper course. It is worth bringing to the attention of other crews to be vigilant of the CRJs automation as I have also experienced the speed mode changing from 250 knots to 40 knots without command from the crew.
Data retrieved from NASA's ASRS site as of April 2012 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.