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Cases › WPR12LA119 · Part 121 airline

BOEING 737-7H4SOUTHWEST AIRLINES CO

Pawnee, NE, USA · 2012-02-23·N915WN

0
fatal
1
serious
Serious injury
highest injury
—
damage
Replay the flight data1,182,747 samples · 28 parameters13:13:18.0 – 17:43:19.9AnalyseThe analystOne timeline · precedents · ask the docket · what the record saysGenerateInvestigation briefFacts, cause, recorder extremes, sequence, sourcesSourceNTSB docket6 documents on data.ntsb.gov

What happened

NTSB summary, verbatim

The airplane had been cruising in smooth air conditions for over 30 minutes when it suddenly encountered 2 to 3 seconds of moderate turbulence. The momentary altitude and roll deviation of the airplane, which was corrected by the autopilot, threw one of the flight attendants against the airplane structure, which resulted in a serious injury to her hand. The flight crew had not been given any turbulence advisories by air route traffic controllers, and the flight crew had not overheard any airplanes in the area reporting moderate turbulence. Immediately after the encounter, the airplane continued in smooth air conditions.

Photographs

1the aircraft, and what the investigators found
The aircraft before the accident
N915WN (15887025671)
redlegsfan21 · CC BY-SA 2.0 · Wikimedia Commons

Probable cause

the Board's determination
The airplane's encounter with moderate turbulence during cruise flight, which resulted in a serious injury to a flight attendant.

Occurrence sequence

1 stepsNTSB coding · CICTT taxonomy
  1. 1 · Enroute-cruise
    Turbulence encounter
    defining event

Findings

1 causal · 1 contributing
  • CAUSE
    Environmental issues › Conditions/weather/phenomena › Turbulence › Clear air turbulence — Effect on operation
  • FACTOR
    Personnel issues › Physical › Impairment/incapacitation › Illness/injury — Cabin crew

Sequence of events

3 timed eventsfrom the FDR factual report · claude-sonnet-5
  1. 1924:30 GMTClimb/Cruisep.2
    Start of data shown in Figure 1, aircraft initially climbed to flight level 340 and then continued to flight level 360
  2. 2030 GMTCruisep.2
    Crew reported upset time; assumed to occur at flight level 360 in level, cruise flight, about 1 hour after take-off
  3. 2354:30 GMTCruise/Descentp.2
    End of data shown in Figure 1

NTSB analysis

from the final report

The airplane had been cruising in smooth air conditions for over 30 minutes when it suddenly encountered 2 to 3 seconds of moderate turbulence. The momentary altitude and roll deviation of the airplane, which was corrected by the autopilot, threw one of the flight attendants against the airplane structure, which resulted in a serious injury to her hand. The flight crew had not been given any turbulence advisories by air route traffic controllers, and the flight crew had not overheard any airplanes in the area reporting moderate turbulence. Immediately after the encounter, the airplane continued in smooth air conditions.