 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Light transport aircraft. Crew encounters extreme up and downdrafts associated with convective activity. Aircraft control is almost lost in the upset.
| Attributes | |
| ACN | 409600 |
| Time | |
| Date | 199807 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : flo |
| State Reference | SC |
| Altitude | msl bound lower : 36000 msl bound upper : 38000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc |
| Operator | general aviation : corporate |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 85 flight time total : 8500 flight time type : 2500 |
| ASRS Report | 409600 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance other anomaly other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : exited adverse environment flight crew : regained aircraft control flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Aircraft in cruise flight, IMC, occasional light turbulence, thunderstorms in area. No radar returns for route of flight ahead. For no apparent reason, airspeed increased and aircraft climbed from FL370 assigned altitude (autoplt on, altitude hold, turbulence mode). Captain reduced power, disengaged autoplt and pitched aircraft down. Aircraft began to oscillate in pitch and altitude/airspeed between 38000 ft and 36000 ft/290 KIAS (and above redline) to 170 KIAS. The aircraft behaved as if it had encountered a mountain wave. Center was notified and had no conflicts. The pitch trim was apparently trying to keep up with the power/pitch changes and (we think) over compensated. The pitch trim circuit breaker was pulled, and the captain regained control and restabilized the aircraft at FL370. Rest of the flight was uneventful. Don't know why this happened. There are no 15000 ft mountains in sc and winds aloft were quartering tail at about 70 KTS. Possible convective activity in the area could have been a factor but you never would have guessed it.
Original NASA ASRS Text
Title: LTT ACFT. CREW ENCOUNTERS EXTREME UP AND DOWNDRAFTS ASSOCIATED WITH CONVECTIVE ACTIVITY. ACFT CTL IS ALMOST LOST IN THE UPSET.
Narrative: ACFT IN CRUISE FLT, IMC, OCCASIONAL LIGHT TURB, TSTMS IN AREA. NO RADAR RETURNS FOR RTE OF FLT AHEAD. FOR NO APPARENT REASON, AIRSPD INCREASED AND ACFT CLBED FROM FL370 ASSIGNED ALT (AUTOPLT ON, ALT HOLD, TURB MODE). CAPT REDUCED PWR, DISENGAGED AUTOPLT AND PITCHED ACFT DOWN. ACFT BEGAN TO OSCILLATE IN PITCH AND ALT/AIRSPD BTWN 38000 FT AND 36000 FT/290 KIAS (AND ABOVE REDLINE) TO 170 KIAS. THE ACFT BEHAVED AS IF IT HAD ENCOUNTERED A MOUNTAIN WAVE. CTR WAS NOTIFIED AND HAD NO CONFLICTS. THE PITCH TRIM WAS APPARENTLY TRYING TO KEEP UP WITH THE PWR/PITCH CHANGES AND (WE THINK) OVER COMPENSATED. THE PITCH TRIM CIRCUIT BREAKER WAS PULLED, AND THE CAPT REGAINED CTL AND RESTABILIZED THE ACFT AT FL370. REST OF THE FLT WAS UNEVENTFUL. DON'T KNOW WHY THIS HAPPENED. THERE ARE NO 15000 FT MOUNTAINS IN SC AND WINDS ALOFT WERE QUARTERING TAIL AT ABOUT 70 KTS. POSSIBLE CONVECTIVE ACTIVITY IN THE AREA COULD HAVE BEEN A FACTOR BUT YOU NEVER WOULD HAVE GUESSED IT.
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.