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A320 flight crew encounters mountain wave activity, exceeds the aircraft's maximum operating speed (vmo) and deviates from assigned altitude.
| Attributes | |
| ACN | 568853 |
| Time | |
| Date | 200212 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : zzz.artcc |
| State Reference | US |
| Altitude | msl single value : 30000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : flight engineer pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 7000 flight time type : 200 |
| ASRS Report | 568853 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter : turbulence non adherence : far other anomaly |
| Independent Detector | aircraft equipment other aircraft equipment : acft overspeed warning other flight crewa other flight crewb |
| Resolutory Action | flight crew : returned to assigned altitude flight crew : overrode automation |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance Weather |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While in cruise flight and level at altitude (indicated airspeed was .80 mach), severe mountain wave or windshear was encountered. This caused indicated airspeed to unexpectedly and rapidly increase to approximately 10 KTS past vmo. Autoplt disconnected and aircraft automatically pitched up which caused altitude deviation. Autothrottles were disconnected, forward stick was input to counter pitch up, and speed brakes were deployed. These actions decreased potential altitude deviation by as much as 1000-2000 ft. As airspeed decreased, recovery was made within approximately 1 min. WX was smooth and clear with no known PIREPS alerting us to wave/shear encountered. Altitude deviation was solely caused by airbus design. Airspeed deviation could have easily been corrected almost as fast without automatic aircraft pitch up.
Original NASA ASRS Text
Title: A320 FLC ENCOUNTERS MOUNTAIN WAVE ACTIVITY, EXCEEDS THE ACFT'S MAX OPERATING SPD (VMO) AND DEVIATES FROM ASSIGNED ALT.
Narrative: WHILE IN CRUISE FLT AND LEVEL AT ALT (INDICATED AIRSPD WAS .80 MACH), SEVERE MOUNTAIN WAVE OR WINDSHEAR WAS ENCOUNTERED. THIS CAUSED INDICATED AIRSPD TO UNEXPECTEDLY AND RAPIDLY INCREASE TO APPROX 10 KTS PAST VMO. AUTOPLT DISCONNECTED AND ACFT AUTOMATICALLY PITCHED UP WHICH CAUSED ALTDEV. AUTOTHROTTLES WERE DISCONNECTED, FORWARD STICK WAS INPUT TO COUNTER PITCH UP, AND SPD BRAKES WERE DEPLOYED. THESE ACTIONS DECREASED POTENTIAL ALTDEV BY AS MUCH AS 1000-2000 FT. AS AIRSPD DECREASED, RECOVERY WAS MADE WITHIN APPROX 1 MIN. WX WAS SMOOTH AND CLR WITH NO KNOWN PIREPS ALERTING US TO WAVE/SHEAR ENCOUNTERED. ALTDEV WAS SOLELY CAUSED BY AIRBUS DESIGN. AIRSPD DEV COULD HAVE EASILY BEEN CORRECTED ALMOST AS FAST WITHOUT AUTOMATIC ACFT PITCH UP.
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.