37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Attributes | |
ACN | 1043552 |
Time | |
Date | 201210 |
Local Time Of Day | 1801-2400 |
Place | |
Locale Reference | MEM.Airport |
State Reference | TN |
Environment | |
Flight Conditions | VMC |
Light | Night |
Aircraft 1 | |
Make Model Name | A300 |
Operating Under FAR Part | Part 121 |
Flight Phase | Descent |
Flight Plan | IFR |
Component | |
Aircraft Component | FMS/FMC |
Person 1 | |
Function | Captain Pilot Flying |
Qualification | Flight Crew Air Transport Pilot (ATP) |
Person 2 | |
Function | Pilot Not Flying First Officer |
Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Engineer |
Events | |
Anomaly | Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types |
Narrative:
As we approached arg; we were cleared to descend via the FNCHR1 RNAV STAR. All altitude and airspeed constraints were previously reviewed and confirmed by the crew during the approach briefing. The only modifications to the [line selected] FMS procedure were to change the cost index to 132 just prior to top of descent; and the deletion of the 'vector leg' after jaywa in order to provide a more accurate fuel prediction figure for landing. The arrival was flown in profile with the altitude select window set and confirmed for 4;000 ft (the lowest altitude on FNCHR1 arrival at jaywa). All altitude and airspeed constraints were satisfied for all points from start of arrival through crossing loonr waypoint. After crossing loonr at 9;000 and 210 KTS; aircraft continued descent in profile for the 'at or above' 8;000 crossing restriction at bowen. Passing through approximately 8;700 ft; the aircraft pitched over with rapidly increasing airspeed; though target airspeed still displayed 210 KTS and crossing restriction at bowen still showed 8;000 on the FMS and the constraints display. I initially attempted to control the airspeed increase with speed brakes; but it became apparent that further action would be required to correct the deviation. I then disconnected the autopilot to arrest the descent and increasing airspeed. We crossed bowen at approximately 7;700 and 240 KTS. We stopped the descent at 7;500 ft and slowed to 210 KTS before continuing the descent via the FNCHR1 arrival during which approach cleared us to stop our descent at 6;000. The remainder of arrival and approach proceeded normally.I believe I need to take more aggressive action to arrest deviations on profile descents. Also; after observing and hearing the number of constraint deviations that are occurring with airbus RNAV arrivals that are flown in profile; I recommend airbus arrivals be flown in lvl/ch.
Original NASA ASRS Text
Title: An A300 flight crew descending via the FNCHR RNAV STAR to MEM was surprised when the FMS inexplicably increased their rate of descent and airspeed and crossed BOWEN 300 FT low and 30 KIAS fast. They disconnected autoflight and returned to their clearance. The analyst is not a champion of attempting to manually manage crossing restrictions on Optimized RNAV STARs as doing so often requires excessive flight crew workload; often at the expense of other high priority tasks. Vertical Navigation autoflight functions should be capable of complying with the demands of a complex vertical flight path and if failures to do so occur with any degree of frequency either the STAR or the aircraft should be examined for compatibility problems.
Narrative: As we approached ARG; we were cleared to descend via the FNCHR1 RNAV STAR. All altitude and airspeed constraints were previously reviewed and confirmed by the crew during the approach briefing. The only modifications to the [line selected] FMS procedure were to change the Cost Index to 132 just prior to top of descent; and the deletion of the 'vector leg' after JAYWA in order to provide a more accurate Fuel Prediction figure for landing. The arrival was flown in Profile with the Altitude Select window set and confirmed for 4;000 FT (The lowest altitude on FNCHR1 arrival at JAYWA). All altitude and airspeed constraints were satisfied for all points from start of arrival through crossing LOONR waypoint. After crossing LOONR at 9;000 and 210 KTS; aircraft continued descent in Profile for the 'at or above' 8;000 crossing restriction at BOWEN. Passing through approximately 8;700 FT; the aircraft pitched over with rapidly increasing airspeed; though target airspeed still displayed 210 KTS and crossing restriction at BOWEN still showed 8;000 on the FMS and the constraints display. I initially attempted to control the airspeed increase with speed brakes; but it became apparent that further action would be required to correct the deviation. I then disconnected the autopilot to arrest the descent and increasing airspeed. We crossed BOWEN at approximately 7;700 and 240 KTS. We stopped the descent at 7;500 FT and slowed to 210 KTS before continuing the descent via the FNCHR1 arrival during which Approach cleared us to stop our descent at 6;000. The remainder of arrival and approach proceeded normally.I believe I need to take more aggressive action to arrest deviations on profile descents. Also; after observing and hearing the number of constraint deviations that are occurring with Airbus RNAV arrivals that are flown in Profile; I recommend Airbus arrivals be flown in LVL/CH.
Data retrieved from NASA's ASRS site as of July 2013 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.