Narrative:
During cruise at FL330 the aircraft encountered turbulence while passing through isolated, embedded cb. Two particularly strong gusts were experienced, leading to major nose-up excursions, one reaching 26 degrees. Autopilot and autothrottle disengaged and the stick shaker activated. The pilot appeared to have made strong, long-duration nose-up inputs, despite the stick shaker, and there was no evidence of attempts at stall recovery. The longitudinal stability augmentation system (LSAS) did not fail and would have operated before the stick shaker. It is therefore assumed that the pilot's inputs overrode the LSAS. Both outboard elevators were found to be damaged on arrival, due to operation outside the design envelope.
Loss of control
| Status: | Accident Investigation report not yet completed, but information verified through authorities or other sources. |
| Date: | Thursday 26 August 1993 |
| Time: | 19:30 |
| Type: |  McDonnell Douglas MD-11C |
| Operator: | Alitalia |
| Registration: | I-DUPU |
| MSN: | 48430/508 |
| First flight: | 1992 |
| Engines: | 3 General Electric CF6-80C2D1F |
| Crew: | Fatalities: 0 / Occupants: |
| Passengers: | Fatalities: 0 / Occupants: |
| Total: | Fatalities: 0 / Occupants: |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | over Boulder, NV ( United States of America)
|
| Phase: | En route (ENR) |
| Nature: | International Scheduled Passenger |
| Departure airport: | Los Angeles International Airport, CA (LAX/KLAX), United States of America |
| Roma-Fiumicino Airport (FCO/LIRF), Italy |
During cruise at FL330 the aircraft encountered turbulence while passing through isolated, embedded cb. Two particularly strong gusts were experienced, leading to major nose-up excursions, one reaching 26 degrees. Autopilot and autothrottle disengaged and the stick shaker activated. The pilot appeared to have made strong, long-duration nose-up inputs, despite the stick shaker, and there was no evidence of attempts at stall recovery. The longitudinal stability augmentation system (LSAS) did not fail and would have operated before the stick shaker. It is therefore assumed that the pilot's inputs overrode the LSAS. Both outboard elevators were found to be damaged on arrival, due to operation outside the design envelope.
Classification:
TurbulenceLoss of control
Sources:
» ICAO Summary 3/95Photos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Los Angeles International Airport, CA to Roma-Fiumicino Airport as the crow flies is 10136 km (6335 miles).
Distance from Los Angeles International Airport, CA to Roma-Fiumicino Airport as the crow flies is 10136 km (6335 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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