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Cases › DCA16CA021 · Part 121 airline

BOEING 787UNITED AIR LINES INC

Beaumont, TX, USA · 2015-11-07·N27958

0
fatal
1
serious
Serious injury
highest injury
—
damage
Replay the flight data41,006 samples · 28 parameters00:05:00.0 – 11:28:25.0AnalyseThe 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

According to crew statements, the flight encountered light turbulence while deviating around areas of weather depicted on the onboard weather radar during descent from FL350 to 12,000 feet. Air Traffic Control (ATC) had also advised them of areas of precipitation shown on ATC radar. The seatbelt sign was turned on and the flight crew advised the cabin crew to complete service and be seated for arrival. The flight was returning on course after it appeared they were clear of significant weather when they encountered an area of moderate turbulence and briefly encountered what the crew characterized as severe turbulence. A flight attendant (FA) in the aft galley was lifted into the air and fell back down to the floor injuring her ankle. The flight crew was notified of the injury and they requested paramedics meet the airplane upon arrival. The FA was transported to the hospital where she was diagnosed with a fractured ankle.

Probable cause

the Board's determination
An inadvertent encounter with convective turbulence resulting in serious injury to a flight attendant.

Occurrence sequence

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

Findings

1 causal · 0 contributing
  • CAUSE
    Environmental issues › Conditions/weather/phenomena › Turbulence › Convective turbulence — Effect on personnel

Sequence of events

3 timed eventsfrom the FDR factual report · claude-sonnet-5
  1. 0600 CDT (approx.)Descentp.1
    United Airlines flight #128, a Boeing 787-900, encountered moderate turbulence while descending to Houston G. Bush Intercontinental Airport (IAH)
  2. 10:52:00 to 11:00:00 UTCDescentp.2
    Figure 2 depicts an eight minute segment highlighting increases in acceleration consistent with a turbulence event
  3. 10:55:00 to 10:56:30 UTCDescentp.2
    Increases in all three accelerations are noticeable, consistent with turbulence event

NTSB analysis

from the final report

According to crew statements, the flight encountered light turbulence while deviating around areas of weather depicted on the onboard weather radar during descent from FL350 to 12,000 feet. Air Traffic Control (ATC) had also advised them of areas of precipitation shown on ATC radar. The seatbelt sign was turned on and the flight crew advised the cabin crew to complete service and be seated for arrival. The flight was returning on course after it appeared they were clear of significant weather when they encountered an area of moderate turbulence and briefly encountered what the crew characterized as severe turbulence. A flight attendant (FA) in the aft galley was lifted into the air and fell back down to the floor injuring her ankle. The flight crew was notified of the injury and they requested paramedics meet the airplane upon arrival. The FA was transported to the hospital where she was diagnosed with a fractured ankle.