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Cases › CEN10LA240 · Part 121 airline

BOEING 767American Airlines

Fort Dodge, IA, USA · 2010-04-30·N320AA

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 docket7 documents on data.ntsb.gov

What happened

NTSB summary, verbatim

The scheduled domestic passenger flight encountered turbulence while diverting around an area of convective activity. A flight attendant who was not seated sustained serious injuries and five others on board sustained minor injuries as a result of the turbulence encounter. Flight data recorder information showed that the airplane experienced a vertical acceleration from 0.5 and 2 g’s and an altitude change of 100 feet in each direction.

Photographs

1the aircraft, and what the investigators found
The aircraft before the accident
395aa - American Airlines Boeing 767-223ER, N320AA@LAX,11.02.2006 - Flickr - Aero Icarus
Aero Icarus from Zürich, Switzerland · CC BY-SA 2.0 · Wikimedia Commons

Probable cause

the Board's determination
The flight crew's inadequate separation from convective activity that resulted in serious injury to an unrestrained flight attendant.

Occurrence sequence

2 stepsNTSB coding · CICTT taxonomy
  1. 1 · Enroute-cruise
    Windshear or thunderstorm
    defining event
  2. 2 · Enroute-cruise
    Turbulence encounter

Findings

4 causal · 0 contributing
  • CAUSE
    Environmental issues › Conditions/weather/phenomena › Convective weather › Thunderstorm — Effect on personnel
  • CAUSE
    Environmental issues › Conditions/weather/phenomena › Turbulence › Convective turbulence — Effect on operation
  • CAUSE
    Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Heading/course — Not specified
  • CAUSE
    Aircraft › Aircraft systems › Equipment/furnishings › Passenger compartment equip — Not used/operated

Sequence of events

3 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)
  1. about 2 h 0 min 41 s into the flightcruisep.4
    Cruising at about 41,000 ft and 232 kts with autopilot engaged when the turbulence event began: vertical acceleration fluctuated between -0.5 and 2.0 g, longitudinal between -0.1 and 0.1 g, lateral spiked to 0.2 g and -0.1 g; altitude rose and fell about 100 ft each way; roll as far as 20 deg right; heading changed 20 deg right
  2. about 15 s after onsetcruisep.4
    Captain disengaged the autopilot for about 15 seconds to correct course and regain control
  3. during the eventcruisep.4
    Total pressure spiked from 270 mb to 300 mb; wind direction shifted about 20 deg left, accounted for by the 20 deg right heading change; no sudden changes in wind or pressure before the event

NTSB analysis

from the final report

The scheduled domestic passenger flight encountered turbulence while diverting around an area of convective activity. A flight attendant who was not seated sustained serious injuries and five others on board sustained minor injuries as a result of the turbulence encounter. Flight data recorder information showed that the airplane experienced a vertical acceleration from 0.5 and 2 g’s and an altitude change of 100 feet in each direction.