BOEING 757 232DELTA AIR LINES INC
Atlanta, GA, USA · 2014-01-10·N687DL
What happened
NTSB summary, verbatimThe flight crew was anticipating light turbulence during the descent and notified the cabin and selected the fasten seatbelt sign on prior to descending from 28,000 feet. During the descent, as the flight attendants (FA) were still preparing the cabin for arrival, the turbulence increased to a level the crew categorized as moderate. During this time, while trying to get to her seat, a FA was thrown against the 3L door and fell to the floor injuring her right ankle. The FA could not complete her duties and was assisted into the last row of seats. Another FA informed the flight crew who arranged for paramedics to meet the airplane. The FA was transported to the hospital and diagnosed with a broken right tibia in two places.
Probable cause
the Board's determinationunexpected encounter with convective turbulence while the flight attendants were preparing for arrival.
Occurrence sequence
1 stepsNTSB coding · CICTT taxonomy- 1 · Enroute-descentTurbulence encounterdefining event
Findings
1 causal · 0 contributing- CAUSEEnvironmental issues › Conditions/weather/phenomena › Turbulence › Convective turbulence — Effect on personnel
Sequence of events
5 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)- 06:20 ESTtakeoffp.2Aircraft took off and climbed to a cruising pressure altitude of about 29,000 ft
- about 06:38 ESTcruisep.2Pressure altitude decreased to 28,000 ft about 3 minutes before the descent began
- 06:41 ESTdescentp.2Gradual descent began; over the next few minutes there were some perturbations in the acceleration parameters
- 06:46:33 ESTdescentp.3A more pronounced set of fluctuations in the acceleration parameters lasting about 10 seconds: lateral acceleration went from 0.18 g to -0.12 g within 1 second; vertical acceleration peaked at 1.67 g and dipped to 0.51 g in just over a second; slight roll excursion from about +2.5 degrees right to -6.7 degrees left (turbulence encounter in which a flight attendant was seriously injured)
- 07:06 ESTlandingp.3Aircraft landed at ATL
NTSB analysis
from the final reportThe flight crew was anticipating light turbulence during the descent and notified the cabin and selected the fasten seatbelt sign on prior to descending from 28,000 feet. During the descent, as the flight attendants (FA) were still preparing the cabin for arrival, the turbulence increased to a level the crew categorized as moderate. During this time, while trying to get to her seat, a FA was thrown against the 3L door and fell to the floor injuring her right ankle. The FA could not complete her duties and was assisted into the last row of seats. Another FA informed the flight crew who arranged for paramedics to meet the airplane. The FA was transported to the hospital and diagnosed with a broken right tibia in two places.