BOEING 777-232DELTA AIR LINES INC
Atlanta, GA, USA · 2013-07-12·N863DA
What happened
NTSB summary, verbatimAccording to the flight and cabin crew statements, Atlanta Approach Control advised the crew that radar was showing an area of rain on the arrival route although the flight crew did not see any areas of precipitation on the airborne weather radar. During the descent to 11,000 feet the seatbelt sign was illuminated and the captain, who was the pilot monitoring, cycled the seatbelt sign and called the flight attendant (FA) at the 1L door via the interphone to notify the cabin crew to be seated. Before the 1L flight attendant was able to relay the message to all of the FAs to be seated, as they were all preparing the cabin for arrival, the airplane encountered several distinct jolts of turbulence. According to the flight data recorder data, as the airplane was descending through about 13,200 feet, the vertical acceleration fluctuated between +1.56 g's and +0.024 g's over a period of about 10 seconds. During the turbulence the 4Rc FA who was in the aisle near the 3R door was lifted into the air and fell back down to the floor on her feet and knees. The FA was assisted to the 3R jumpseat, the flight crew was notified of the injury, and they requested paramedics meet the airplane upon arrival The 4Rc FA was transported to the hospital where she was diagnosed with two broken ankles.
Photographs
1the aircraft, and what the investigators foundProbable cause
the Board's determinationUnexpected encounter with convective turbulence while the flight attendants were preparing the cabin 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
4 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)- about 15:15 EDT (July 11)takeoffp.2Aircraft departed
- 05:44:03-05:44:27 EDTdescentp.2Presumed turbulence encounter during the descent into ATL
- 05:44:10 EDTdescentp.2In the 10-second period starting here, descending through 13,200 ft pressure altitude, vertical acceleration fluctuated between +1.56 g and +0.24 g; airspeed momentarily increased from 309 to 316 knots; lateral acceleration fluctuated between +0.12 g and -0.19 g; roll fluctuated between 4 degrees left and 5 degrees right
- about 06:00 EDTlandingp.2Aircraft landed, 14 hours 45 minutes after departure
NTSB analysis
from the final reportAccording to the flight and cabin crew statements, Atlanta Approach Control advised the crew that radar was showing an area of rain on the arrival route although the flight crew did not see any areas of precipitation on the airborne weather radar. During the descent to 11,000 feet the seatbelt sign was illuminated and the captain, who was the pilot monitoring, cycled the seatbelt sign and called the flight attendant (FA) at the 1L door via the interphone to notify the cabin crew to be seated. Before the 1L flight attendant was able to relay the message to all of the FAs to be seated, as they were all preparing the cabin for arrival, the airplane encountered several distinct jolts of turbulence. According to the flight data recorder data, as the airplane was descending through about 13,200 feet, the vertical acceleration fluctuated between +1.56 g's and +0.024 g's over a period of about 10 seconds. During the turbulence the 4Rc FA who was in the aisle near the 3R door was lifted into the air and fell back down to the floor on her feet and knees. The FA was assisted to the 3R jumpseat, the flight crew was notified of the injury, and they requested paramedics meet the airplane upon arrival The 4Rc FA was transported to the hospital where she was diagnosed with two broken ankles.