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A B757 experienced flight guidance anomalies at FL380; 25 degree - 30 degree uncommanded roll and autothrottle disconnect.
| Attributes | |
| ACN | 752210 |
| Time | |
| Date | 200709 |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | msl single value : 38000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| 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 |
| Experience | flight time last 90 days : 200 flight time total : 12500 flight time type : 2500 |
| ASRS Report | 752210 |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : regained aircraft control flight crew : overrode automation |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
Aircraft in cruise at FL380 clear. Executed a rapid; uncommanded right bank of 25-30 degrees. Automatic pilot was disconnected by the captain and aircraft was rolled wings level manually. Right and left autopilots operated normally for the remaining 2 hours of the 4 hour flight. The event happened previously and a maintenance bite test found no faults. Captain discussed with dispatch and maintenance and continued to destination using either the left or right autoplt as agreed. Later in the flight the automatic throttle disconnected and was reselected.
Original NASA ASRS Text
Title: A B757 EXPERIENCED FLT GUIDANCE ANOMALIES AT FL380; 25 DEG - 30 DEG UNCOMMANDED ROLL AND AUTOTHROTTLE DISCONNECT.
Narrative: AIRCRAFT IN CRUISE AT FL380 CLEAR. EXECUTED A RAPID; UNCOMMANDED RIGHT BANK OF 25-30 DEGREES. AUTO PILOT WAS DISCONNECTED BY THE CAPTAIN AND AIRCRAFT WAS ROLLED WINGS LEVEL MANUALLY. RIGHT AND LEFT AUTOPILOTS OPERATED NORMALLY FOR THE REMAINING 2 HOURS OF THE 4 HOUR FLIGHT. THE EVENT HAPPENED PREVIOUSLY AND A MAINTENANCE BITE TEST FOUND NO FAULTS. CAPTAIN DISCUSSED WITH DISPATCH AND MAINT AND CONTINUED TO DESTINATION USING EITHER THE LEFT OR RIGHT AUTOPLT AS AGREED. LATER IN THE FLIGHT THE AUTO THROTTLE DISCONNECTED AND WAS RESELECTED.
Data retrieved from NASA's ASRS site as of January 2009 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.