Boeing 737 N3730B accident near Franklin, Tennessee

Probable cause

an encounter with convective turbulence during descent.

NTSB analysis

On February 17, 2019, about 1804 central standard time, Delta Air Lines flight 957, a Boeing 737-800, N3730B, encountered turbulence during descent into Atlanta Hartsfield-Jackson International Airport (KATL), Atlanta, Georgia. Of the 145 passengers and crew onboard, one flight attendant sustained serious injuries and one received minor injuries. The airplane was not damaged. The flight was operating under 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from Bozeman Yellowstone International Airport (KBZN), Bozeman, Montana, to KATL.

According to the flight crew, air traffic control informed them to expect light and occasional moderate turbulence during the descent. About 10 minutes before beginning their descent, the flight crew illuminated the seat belt sign and instructed the flight attendants (FA) to stow the carts and take their seats. Shortly after departing FL350 for FL250, and the airplane encountered two “rapid-bumps of light-moderate turbulence” at approximately FL345. The flight crew slowed the airplane and contacted the FAs and was informed that the aft FA was injured.

According to the flight attendants, the flight had been routine, having experienced only occasional light turbulence. The two aft FAs had finished their meal service and secured the galley. The two FAs were making their final walkthrough of the cabin when the captain made the public address announcement to discontinue cabin service, when the turbulence was encountered. The two aft FAs reported they were thrown up to the ceiling and then came “crashing back down” onto the galley floor. One of the FAs was in intense pain after striking the floor hard and was attended to by two medically qualified passengers. The FA was moved to an empty passenger row for landing and was provided oxygen and pain medication. The flight crew declared an emergency and requested paramedics meet the flight at the gate. The FA was transported to the hospital where she was diagnosed with a fractured vertebra.

Post accident examination of the weather data determined that the accident flight was in instrument meteorological conditions (IMC) in an area of convectively induced turbulence due to embedded rain shower activity when the turbulence was encountered. While there was no lightning activity around the accident site at the accident time, there were pockets of strong rain shower cells within the complex of precipitation as a whole. The area where the accident occurred was covered by AIRMET Tango that warned of moderate turbulence conditions.

Text from the NTSB. Open the NTSB docket for DCA19CA091 for the full record.