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Cases › DCA16CA010 · Part 121 airline

BOEING 737-924ERUNITED AIR LINES INC

Plevna, KS, USA · 2015-10-24·N69838

0
fatal
1
serious
Serious injury
highest injury
—
damage
Replay the flight data12,460 samples · 23 parameters00:00:00.0 – 03:27:39.0AnalyseThe analystOne timeline · precedents · ask the docket · what the record saysGenerateInvestigation briefFacts, cause, recorder extremes, sequence, sourcesSourceNTSB docket8 documents on data.ntsb.gov

What happened

NTSB summary, verbatim

According to flight crew statements, possible moderate turbulence was forecasted for portions of the route of flight and they briefed the flight attendants (FA) of the possible turbulence.  During the first portion of the flight, several areas of turbulence were encountered. The seatbelt sign was turned on during this time and the captain told the FAs to suspend service and remain seated. The flight crew requested and was cleared to a lower altitude and the turbulence subsided.  After the flight was in smooth air for several minutes, the captain advised the FAs they could leave their seats but not use the carts. About five minutes later the flight again encountered moderate to severe turbulence. The captain called the cabin and discovered two FAs in the aft galley had sustained injuries during the encounter but could continue their duties to the destination.  After arrival, the FAs were transported to the hospital where one was diagnosed with a tibia plateau fracture.

Probable cause

the Board's determination
An inadvertent encounter with clear air turbulence resulting 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 · 0 contributing
  • CAUSE
    Environmental issues › Conditions/weather/phenomena › Turbulence › Clear air turbulence — Effect on personnel

Sequence of events

2 timed eventsfrom the FDR factual report · claude-sonnet-5
  1. 0935 CDT (October 25, 2015, per event summary text)enroutep.1
    United Airlines flight #1904 encountered moderate to severe turbulence 20 miles west of ICT at FL270 while enroute to Orlando International Airport (ORD). The seatbelt sign was on. There were no passenger injuries. Two flight attendants reported injuries.
  2. SRN 2980 to 3590turbulence encounterp.2
    Figure 2 is a segment of figure 1 during the turbulence event from SRN 2980 to 3590. Increases in all three accelerations are noticeable during this period.

NTSB analysis

from the final report

According to flight crew statements, possible moderate turbulence was forecasted for portions of the route of flight and they briefed the flight attendants (FA) of the possible turbulence.  During the first portion of the flight, several areas of turbulence were encountered. The seatbelt sign was turned on during this time and the captain told the FAs to suspend service and remain seated. The flight crew requested and was cleared to a lower altitude and the turbulence subsided.  After the flight was in smooth air for several minutes, the captain advised the FAs they could leave their seats but not use the carts. About five minutes later the flight again encountered moderate to severe turbulence. The captain called the cabin and discovered two FAs in the aft galley had sustained injuries during the encounter but could continue their duties to the destination.  After arrival, the FAs were transported to the hospital where one was diagnosed with a tibia plateau fracture.