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Cases › DCA04MA061 · Major investigation

Boeing 777AMERICAN AIRLINES INC

Miami, FL, USA · 2004-07-25·N797AN

0
fatal
1
serious
Serious injury
highest injury
—
damage
AnalyseThe analystOne timeline · precedents · ask the docket · what the record saysGenerateInvestigation briefFacts, cause, recorder extremes, sequence, sourcesSourceNTSB docket0 documents on data.ntsb.gov

What happened

NTSB summary, verbatim

The flight encountered unforecasted clear air turbulence while the flight attendants were providing meal service to the passengers. Several of the flight attendants were thrown to the floor by the turbulence, and a flight attendant operating in the rear of the airplane received a fractured left shoulder. The autopilot was engaged at the time of the event, and there were no pilot inputs during the turbulence encounter. Statements from the captain (the flying pilot) and the first officer indicated that the event involved clear air turbulence that lasted 3-4 seconds. The captain characterized the turbulence encounter as "moderate" and being similar to a wake turbulence encounter because of the extremely short duration. He indicated that there were no aircraft in front of them and the nearest thunderstorms were greater than 20 miles to the northwest. The first officer added that they had received no turbulence warnings from other aircraft and that they were clear of all weather.

Photographs

1the aircraft, and what the investigators found
The aircraft before the accident
American Airlines Boeing 777-200ER (N797AN) (7228557506)
Cory W. Watts from Madison, Wisconsin, United States of America · CC BY-SA 2.0 · Wikimedia Commons

Probable cause

the Board's determination
the in-flight encounter with unforecasted clear air turbulence.

NTSB analysis

from the final report

The flight encountered unforecasted clear air turbulence while the flight attendants were providing meal service to the passengers. Several of the flight attendants were thrown to the floor by the turbulence, and a flight attendant operating in the rear of the airplane received a fractured left shoulder. The autopilot was engaged at the time of the event, and there were no pilot inputs during the turbulence encounter. Statements from the captain (the flying pilot) and the first officer indicated that the event involved clear air turbulence that lasted 3-4 seconds. The captain characterized the turbulence encounter as "moderate" and being similar to a wake turbulence encounter because of the extremely short duration. He indicated that there were no aircraft in front of them and the nearest thunderstorms were greater than 20 miles to the northwest. The first officer added that they had received no turbulence warnings from other aircraft and that they were clear of all weather.