Airbus A319-112 N951FR accident near Fort Lauderdale, Florida

Probable cause

an inadvertent encounter with convectively induced turbulence developing upwards into the flight path, which was not detected on weather radar as configured by the crew.

Contributing to the delay in emergency medical personnel notification was the incomplete coordination of paramedic response by air traffic control and ineffective communications monitoring by Frontier Airlines.

NTSB analysis

On May 10, 2012, at 1224 Eastern Daylight Time (EDT) an Airbus 319, registration N951FR, operated by Frontier Airlines as flight 384, encountered turbulence resulting in serious injuries to a flight attendant during descent into the Fort Lauderdale Airport (FLL). The flight was descending through 12,400 feet about 45 miles west of FLL at the time of the encounter. The airplane was not damaged.

The flight crew reported that on initial descent into the Fort Lauderdale area they noticed typical Florida summertime cumulus cloud conditions. About 20 minutes before the event, the Captain appropriately briefed the flight attendants to prepare the cabin for landing early and to be seated after completing the initial clean-up. The flight crew subsequently illuminated the seat belt sign during the descent. The flight attendants were still in the process of preparing the cabin for landing when the turbulence was encountered.

During descent, the airplane passed in and out of cloud formations. The crew described, and CVR data is consistent with, passing out of a cloud and noticing a larger developing cumulus in front of them. The autopilot and autothrust were engaged. The crew reported that the radar did not indicate any echoes ahead of them. The Airbus weather radar system includes a Turbulence detection function, which was not used by the crew. The Airbus flight crew training manual describes effective mode, range, and tilt settings for detecting “wet” (convective) turbulence. As the airplane passed into the cumulus development, the airplane encountered convectively induced turbulence, resulting in a peak vertical acceleration of about +2 G and -0.5 G. The activity was likely developing upwards, possibly below the field of view of the radar, and into the flight path.

As a result of the injuries to the forward flight attendant, the flight crew advised ATC that they had an injured crew member and requested priority handling and for paramedics to meet the airplane on arrival. The ATC approach controller did not forward the request for paramedics. The crew also attempted to contact the company station agents and dispatch, but received no response. The lack of ATC coordination, and lack of company personnel to monitor communications from inbound flights, delayed the arrival of emergency medical personnel to meet the flight.

Text from the NTSB. Open the NTSB docket for DCA12FA069 for the full record.