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An A319 departed its assigned altitude and exceeded the aircraft redline during a strong mountain wave encounter.
| Attributes | |
| ACN | 869171 |
| Time | |
| Date | 201001 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZLC.ARTCC |
| State Reference | UT |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | A319 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 20000 Flight Crew Type 10000 |
| Person 2 | |
| Function | First Officer Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 180 Flight Crew Total 8000 Flight Crew Type 2000 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence |
Narrative:
We switched ATC frequencies and were told by the new controller that we could expect some moderate chop in 40 miles. I immediately turned the seatbelt on and asked the first officer to seat both the passengers and flight attendants. We were on top of an overcast layer but up ahead I could see some 'mares' tails' type clouds extending across our flight path and appearing to have a small rolling motion. Within about a minute we hit a very strong mountain wave. Our speed immediately went 15 knots over the redline and we began to climb. We informed ATC of our inability to maintain FL390. I disconnected the autothrottles and autopilot and maintained attitude; lowering the nose as soon as the airplane would let me (after speed dropped back below redline). The highest altitude achieved was 40;200 feet and lowest was 38;700 before being able to return to and maintain FL390. No flight attendants or passengers were injured. They were in their seats before we hit the wave. It also was not a very turbulent wave--we only experienced light or maybe light to moderate chop. I believe the airplane g-loads varied between +1.5 and +0.5
Original NASA ASRS Text
Title: An A319 departed its assigned altitude and exceeded the aircraft redline during a strong mountain wave encounter.
Narrative: We switched ATC frequencies and were told by the new Controller that we could expect some moderate chop in 40 miles. I immediately turned the seatbelt on and asked the First Officer to seat both the passengers and flight attendants. We were on top of an overcast layer but up ahead I could see some 'mares' tails' type clouds extending across our flight path and appearing to have a small rolling motion. Within about a minute we hit a very strong mountain wave. Our speed immediately went 15 knots over the redline and we began to climb. We informed ATC of our inability to maintain FL390. I disconnected the autothrottles and autopilot and maintained attitude; lowering the nose as soon as the airplane would let me (after speed dropped back below redline). The highest altitude achieved was 40;200 feet and lowest was 38;700 before being able to return to and maintain FL390. No flight attendants or passengers were injured. They were in their seats before we hit the wave. It also was not a very turbulent wave--we only experienced light or maybe light to moderate chop. I believe the airplane G-loads varied between +1.5 and +0.5
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.