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Flight crew of an air carrier widebody transport lost control of the aircraft speed and pitch control when the aircraft reacted to severe clear air turbulence.
| Attributes | |
| ACN | 334040 |
| Time | |
| Date | 199604 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : elp |
| State Reference | TX |
| Altitude | msl bound lower : 28000 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab |
| Operator | common carrier : air carrier |
| Make Model Name | A300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 240 flight time total : 5100 flight time type : 230 |
| ASRS Report | 334040 |
| Person 2 | |
| Affiliation | company : air carrier |
| 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 | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : regained aircraft control flight crew : exited adverse environment |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | other |
Narrative:
At cruise FL310, over texas on direct route clearance to elp, in clear flying conditions we encountered severe clear air turbulence which started with a rapid pitch down tendency and rapid speed increase that resulted in speed clacker activation then followed by a rapid pitch up tendency and a rapid speed decrease which resulted in low speed buffet vibrations. To recover from the situation we immediately lowered the nose and applied power to recover the airspeed while advising ZAB of our actions of leaving FL310 with a request of a block altitudes of FL280 to FL310. The initial response from the controller was 'I did not clear you to go down' which was later followed by a clearance for block altitudes of FL280 to FL310. We recovered normal speed at about FL295 and continued down to FL280 for the remainder of the flight. There were no injuries reported on the flight. An air carrier flight which was in trail reported rapid fluctuations of airspeed at cruise flight.
Original NASA ASRS Text
Title: FLC OF AN ACR WDB LOST CTL OF THE ACFT SPD AND PITCH CTL WHEN THE ACFT REACTED TO SEVERE CLR AIR TURB.
Narrative: AT CRUISE FL310, OVER TEXAS ON DIRECT RTE CLRNC TO ELP, IN CLR FLYING CONDITIONS WE ENCOUNTERED SEVERE CLR AIR TURB WHICH STARTED WITH A RAPID PITCH DOWN TENDENCY AND RAPID SPD INCREASE THAT RESULTED IN SPD CLACKER ACTIVATION THEN FOLLOWED BY A RAPID PITCH UP TENDENCY AND A RAPID SPD DECREASE WHICH RESULTED IN LOW SPD BUFFET VIBRATIONS. TO RECOVER FROM THE SIT WE IMMEDIATELY LOWERED THE NOSE AND APPLIED PWR TO RECOVER THE AIRSPD WHILE ADVISING ZAB OF OUR ACTIONS OF LEAVING FL310 WITH A REQUEST OF A BLOCK ALTS OF FL280 TO FL310. THE INITIAL RESPONSE FROM THE CTLR WAS 'I DID NOT CLR YOU TO GO DOWN' WHICH WAS LATER FOLLOWED BY A CLRNC FOR BLOCK ALTS OF FL280 TO FL310. WE RECOVERED NORMAL SPD AT ABOUT FL295 AND CONTINUED DOWN TO FL280 FOR THE REMAINDER OF THE FLT. THERE WERE NO INJURIES RPTED ON THE FLT. AN ACR FLT WHICH WAS IN TRAIL RPTED RAPID FLUCTUATIONS OF AIRSPD AT CRUISE FLT.
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.