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A cpr twin jet loses 700 ft during an encounter with severe turbulence. The autoplt altitude hold was unable to cope with this event.
| Attributes | |
| ACN | 398845 |
| Time | |
| Date | 199804 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : pit |
| State Reference | PA |
| Altitude | msl bound lower : 36300 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob tower : dtw |
| 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 : instrument pilot : atp |
| Experience | flight time last 90 days : 75 flight time total : 3800 flight time type : 250 |
| ASRS Report | 398845 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly |
| Independent Detector | 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 | Pilot Deviation |
Narrative:
During level cruise flight at FL370, we experienced severe turbulence. The autoplt was engaged as the aircraft climbed 100 ft then descended approximately 400 ft. After realizing the autoplt was not going to recapture the assigned altitude, I disengaged the autoplt but lost another 300 ft before starting a climb back to our assigned altitude of FL370. In all, we lost 700 ft from our assigned altitude. We informed center of our encounter with severe turbulence and subsequent loss of altitude and asked for a lower altitude. Center immediately assigned us an altitude of FL330. The remainder of the flight was uneventful.
Original NASA ASRS Text
Title: A CPR TWIN JET LOSES 700 FT DURING AN ENCOUNTER WITH SEVERE TURB. THE AUTOPLT ALT HOLD WAS UNABLE TO COPE WITH THIS EVENT.
Narrative: DURING LEVEL CRUISE FLT AT FL370, WE EXPERIENCED SEVERE TURB. THE AUTOPLT WAS ENGAGED AS THE ACFT CLBED 100 FT THEN DSNDED APPROX 400 FT. AFTER REALIZING THE AUTOPLT WAS NOT GOING TO RECAPTURE THE ASSIGNED ALT, I DISENGAGED THE AUTOPLT BUT LOST ANOTHER 300 FT BEFORE STARTING A CLB BACK TO OUR ASSIGNED ALT OF FL370. IN ALL, WE LOST 700 FT FROM OUR ASSIGNED ALT. WE INFORMED CTR OF OUR ENCOUNTER WITH SEVERE TURB AND SUBSEQUENT LOSS OF ALT AND ASKED FOR A LOWER ALT. CTR IMMEDIATELY ASSIGNED US AN ALT OF FL330. THE REMAINDER OF THE FLT WAS UNEVENTFUL.
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.