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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Aircraft equipment problem. Uncommanded autothrottles went to idle power. As airspeed decreased, aircraft descended to maintain speed. Flight crew lost 2000 ft before noticing the descent. Conversation distraction.
| Attributes | |
| ACN | 338360 |
| Time | |
| Date | 199606 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : yna |
| State Reference | PQ |
| Altitude | msl bound lower : 31000 msl bound upper : 33000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute : direct enroute : on vectors enroute airway : czqx |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 30000 flight time type : 800 |
| ASRS Report | 338360 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 18000 flight time type : 5000 |
| ASRS Report | 338371 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were en route from london to houston. We were at FL330 with a pilot discretion climb to FL350. At the time of the event, there was a conversation going in the cockpit. I was the PNF. I glanced at the instruments and noticed that we were in a shallow descent. I manually turned off the autoplt and stopped the descent, then the PF climbed back to the assigned altitude. The cause of the descent was the autothrottle system had reduced speed/power to the point where the aircraft could not maintain altitude. Close to 2000 ft was lost.
Original NASA ASRS Text
Title: ACFT EQUIP PROB. UNCOMMANDED AUTOTHROTTLES WENT TO IDLE PWR. AS AIRSPD DECREASED, ACFT DSNDED TO MAINTAIN SPD. FLC LOST 2000 FT BEFORE NOTICING THE DSCNT. CONVERSATION DISTR.
Narrative: WE WERE ENRTE FROM LONDON TO HOUSTON. WE WERE AT FL330 WITH A PLT DISCRETION CLB TO FL350. AT THE TIME OF THE EVENT, THERE WAS A CONVERSATION GOING IN THE COCKPIT. I WAS THE PNF. I GLANCED AT THE INSTS AND NOTICED THAT WE WERE IN A SHALLOW DSCNT. I MANUALLY TURNED OFF THE AUTOPLT AND STOPPED THE DSCNT, THEN THE PF CLBED BACK TO THE ASSIGNED ALT. THE CAUSE OF THE DSCNT WAS THE AUTOTHROTTLE SYS HAD REDUCED SPD/PWR TO THE POINT WHERE THE ACFT COULD NOT MAINTAIN ALT. CLOSE TO 2000 FT WAS LOST.
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.