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A321 flight crew reported the aircraft failed to honor a properly programmed altitude constraint on descent in managed speed and managed vertical path mode.
| Attributes | |
| ACN | 1570097 |
| Time | |
| Date | 201808 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZBW.ARTCC |
| State Reference | NH |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | A321 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Route In Use | STAR JFUND 2 |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | First Officer Pilot Flying |
| Qualification | Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine |
| Experience | Flight Crew Total 15000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Overshoot Deviation - Procedural Clearance |
Narrative:
I was pilot flying. We were assigned to descend via the JFUND2/runway 04R transition. We had separately confirmed all constraints in the FMC; and I had briefed the arrival. We had left FL270 prior to the first altitude restriction using managed descent. The first constraint was at or above FL240 at mnsta. We were in both managed airspeed and managed vertical path. I was reviewing the taxi plan and gate information when we noticed the aircraft had descended below FL240 about 800 feet prior to the fix. I immediately selected vs (vertical speed) and then initiated a short climb to FL240. We continued to used managed descent and the aircraft met all [other] constraints. I have no idea why the aircraft did not perform as expected and desired. This was the way we were trained to fly the airbus. We were tired and that could have contributed to the problem. Pilots should be trained not to trust the managed descent mode or not use it.
Original NASA ASRS Text
Title: A321 flight crew reported the aircraft failed to honor a properly programmed altitude constraint on descent in managed speed and managed vertical path mode.
Narrative: I was Pilot Flying. We were assigned to descend via the JFUND2/Runway 04R transition. We had separately confirmed all constraints in the FMC; and I had briefed the arrival. We had left FL270 prior to the first altitude restriction using managed descent. The first constraint was at or above FL240 at MNSTA. We were in both managed airspeed and managed vertical path. I was reviewing the taxi plan and gate information when we noticed the aircraft had descended below FL240 about 800 feet prior to the fix. I immediately selected VS (Vertical Speed) and then initiated a short climb to FL240. We continued to used managed descent and the aircraft met all [other] constraints. I have no idea why the aircraft did not perform as expected and desired. This was the way we were trained to fly the Airbus. We were tired and that could have contributed to the problem. Pilots should be trained not to trust the managed descent mode or not use it.
Data retrieved from NASA's ASRS site 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.