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B727 crew had altitude and heading excursions while dealing with an erratic and malfunctioning autoplt.
| Attributes | |
| ACN | 417331 |
| Time | |
| Date | 199810 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : mgm |
| State Reference | AL |
| Altitude | msl bound lower : 33000 msl bound upper : 33400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| ASRS Report | 417331 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 417330 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance other anomaly other other spatial deviation |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Approaching mgm VOR, ARTCC asked our altitude. The center altimeter read FL330.5. The captain and first officer altimeter read FL332. The ivsi appeared to read 100 FPM climb. The captain turned off the altitude hold function of the autoplt to descend to FL330. The jet immediately and aggressively pitched up. The captain quickly disconnected the autoplt and hand flew the jet back down to FL330. The jet's pitch up resulted in a climb to FL334 before the captain reversed the autoplt pitch input. Mgm VOR was a turn point on our flight plan. The next point was otk when the autoplt was disconnected and subsequent recovery completed. The turn was made to otk. Approximately 1/2 way through the turn, ARTCC inquired about our heading. We ended up about 7 mi off course. We asked ARTCC if our situation may have resulted in any potential conflicts and ARTCC said no. Once back on course and aircraft trimmed up, the autoplt was re-engaged. The aircraft immediately made a hard right turn and slight pitch up. The autoplt was again disconnected and left off for the remainder of the flight.
Original NASA ASRS Text
Title: B727 CREW HAD ALT AND HDG EXCURSIONS WHILE DEALING WITH AN ERRATIC AND MALFUNCTIONING AUTOPLT.
Narrative: APCHING MGM VOR, ARTCC ASKED OUR ALT. THE CTR ALTIMETER READ FL330.5. THE CAPT AND FO ALTIMETER READ FL332. THE IVSI APPEARED TO READ 100 FPM CLB. THE CAPT TURNED OFF THE ALT HOLD FUNCTION OF THE AUTOPLT TO DSND TO FL330. THE JET IMMEDIATELY AND AGGRESSIVELY PITCHED UP. THE CAPT QUICKLY DISCONNECTED THE AUTOPLT AND HAND FLEW THE JET BACK DOWN TO FL330. THE JET'S PITCH UP RESULTED IN A CLB TO FL334 BEFORE THE CAPT REVERSED THE AUTOPLT PITCH INPUT. MGM VOR WAS A TURN POINT ON OUR FLT PLAN. THE NEXT POINT WAS OTK WHEN THE AUTOPLT WAS DISCONNECTED AND SUBSEQUENT RECOVERY COMPLETED. THE TURN WAS MADE TO OTK. APPROX 1/2 WAY THROUGH THE TURN, ARTCC INQUIRED ABOUT OUR HDG. WE ENDED UP ABOUT 7 MI OFF COURSE. WE ASKED ARTCC IF OUR SIT MAY HAVE RESULTED IN ANY POTENTIAL CONFLICTS AND ARTCC SAID NO. ONCE BACK ON COURSE AND ACFT TRIMMED UP, THE AUTOPLT WAS RE-ENGAGED. THE ACFT IMMEDIATELY MADE A HARD R TURN AND SLIGHT PITCH UP. THE AUTOPLT WAS AGAIN DISCONNECTED AND LEFT OFF FOR THE REMAINDER OF THE FLT.
Data retrieved from NASA's ASRS site as of July 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.