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On May 10, 2012, at 1224 Eastern Daylight Time (EDT) an Airbus 319, registration N951FR, operated by Frontier Airlines as flight 384, encountered turbulence during descent into the Fort Lauderdale-Hollywood International Airport, Fort Lauderdale, Florida (FLL). The regularly scheduled passenger flight originated from Denver International Airport, Denver Colorado, at 0710 Mountain Standard Time (MST). The flight was descending through 12,400 feet about 45 miles west of FLL on the JINGL1 Standard Terminal Arrival Route (STAR) at the time of the encounter. The encounter resulted in one serious injury and two minor injuries to the three flight attendants onboard. There were no injuries to the two flight crew members or 138 passengers, which included one lap child. The airplane was not damaged.
The crew reported that on initial descent into the FLL area, they noticed the “usual Florida summertime buildups” and decided to turn on the seat belt sign early, although there were no specific reports of adverse conditions. About 20 minutes before the turbulence encounter, the Captain (CA) briefed the Flight Attendants (FAs) that he wanted them seated early and to clean the cabin and be seated when the seat belt sign came on because he expected some turbulence. As the airplane was descending through 25,000 feet he illuminated the seatbelt sign. The weather radar mode was set to “Weather Only” and at approximately this time, both CA and FO displays were set to a range of 80 nautical miles, and remained so throughout the flight. Radar tilt setting is not recorded. At 1219, as the airplane descended through about 21,000 feet, ATC instructed the crew to maintain 300 knots or greater for intrail spacing. At 1224, as the flight descended through 13,000 feet just outside of JINGL intersection the airplane encountered a “short moderate jolt” as described by the crew, for about 5-10 seconds. The cockpit voice recorder (CVR) indicated the first officer remarking that they were about to hit a turbulent area as they neared an isolated cloud. The crew reported that they had just emerged from another cloud when they saw the large build-up. The Flight Data Recorder (FDR) indicated approximately a +2/-0.5 G excursion. The autopilot and autothrust were engaged and the crew made no manual inputs to the flight controls. The crew reported that they were “not painting any weather” on the radar.
Immediately after the turbulence encounter, the crew heard a crash in the galley and called the FAs to ask if they were alright. The forward flight attendant, who was securing the galley by pouring out coffee in the lavatory, was thrown to the floor and twisted her legs in the lavatory door opening. The cabin crew advised the FO that one of them might be hurt. At 1229, the Captain asked Miami Approach Control to make sure there were no delays into FLL and to call for paramedics to meet the flight at the gate. The controller acknowledged, and advised there would be no delay. At 1233, the final controller position split off and a controller briefing occurred, including that Frontier 384 had an injured flight attendant and requested no delay, “but not an emergency.” There was no mention of the request for paramedics. The final controller vectored another aircraft onto an extended downwind to provide priority to the accident flight.
The injured FA was attended by medically qualified passengers in the front aisle. One of the passengers, a surgeon, advised the FA’s right leg was likely broken. The FO tried to contact Frontier Operations at FLL six times with no response, and then tried to contact Frontier Dispatch, via the ACARS text messaging, also with no response. Frontier reported that all station personnel were on the ramp preparing for the arrival. ATC provided priority clearance to the airport and to taxi to the gate, but upon arrival at the gate there were no paramedics. The FO again attempted to contact FLL operations, with no response. The ramp controller (not a Frontier employee) confirmed that there were injuries on board and advised the FO that paramedics were on the way. Shortly afterward, fire crew and paramedics arrived and transported the injured FA to the hospital.
INJURIES TO PERSONS
One flight attendant received a fracture to her right fibula. There were minor injuries reported to the two other flight attendants, however they were able to continue cabin crew duties and safety responsibilities. There were no injuries to the two flight crewmembers, and 138 passengers (including one lap child).
DAMAGE TO AIRCRAFT
Frontier Airlines maintenance performed a post-flight severe turbulence inspection, and reported no findings.
The captain, age 40, held an FAA Airline Transport Pilot certificate, multi-engine land, with type ratings in the A320 and BE-1900. He held an FAA first class medical certificate with no limitations or waivers. He reported a total of 7,586 flight hours total time in the A319.
The first officer, age 41, held an Airline Transport Pilot certificate, multi-engine land, with type ratings in the A320, BE-300, CE-500, and CE-525S. He held an FAA first class medical certificate with no limitations or waivers. He reported a total of 4,837 flight hours total time in the A319.
N951FR, manufacturer serial number 4127, was an Airbus A319-112 equipped with two GE/SNECMA CFM-56 engines. The airplane had approximately 7,408 hours total time on the airframe. Recorded data and airline records indicated no relevant maintenance issues with the airplane.
An NTSB Meteorologist compiled information from the Miami, Florida WSR-88d weather radar (KAMX). At about 1220 EDT, the radar identified a very small area of light reflectivity values (<15 DBz) approximately 30 miles ahead of the accident aircraft’s position. At this point, the accident aircraft was descending through about 23,000 feet. At the location of this reflectivity feature, the KAMX 1.51 degree sweep would have been "seeing" a height of about 10,000 feet (center beam). At about 1226 EDT the radar revealed an intensification of reflectivity values for this feature in the 1.51 degree base reflectivity product. This reflectivity intensification pattern at this height is consistent with developing convection. The accident aircraft's flight path through 1226 EDT indicated that, at some point, the accident aircraft's position between the 1220 and 1226 EDT KAMX radar products was coincident with, or nearly coincident with, the developing convection.
A north-south vertical cross-section of the KAMX base reflectivity data from 1226 EDT between the earth's surface and 20,000 feet indicated that at the time the accident aircraft passed the echoes, the highest reflectivity values (~35 DBz) in the convective cell had reached a height of approximately 12,000 feet.
A thorough review of meteorological data and National Weather Service products for the accident area during the times surrounding the accident time did not identify any mechanism for a significant turbulence encounter beyond the aforementioned developing convection.
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. The FCTM states: “to ensure efficient weather monitoring, the flight crew must effectively manage the tilt…usually the appropriate tilt value provide ground returns on the top of the [display]”. The radar display modes are weather only, weather plus turbulence, turbulence, and mapping. Weather plus turbulence and turbulence modes detect “wet turbulence” within 40 nautical miles.
Following the turbulence encounter, the flight crew was unable to establish communications with company dispatch or station personnel to alert emergency crews. Additionally, the crew’s declaration to ATC approach control regarding the need for paramedics to meet the flight at the gate was not coordinated with tower or other personnel.
The Digital Flight Data Recorder was a Honeywell SSFDR, part number 980-4700-042. The recorder was in good condition and the data were extracted normally from the recorder. DFDR data is incorporated into the History of Flight section of this report.
The Cockpit Voice Recorder was a Honeywell 6022 Solid State CVR that recorded 2 hours of digital cockpit audio. The recording channels which contained the last 30 minutes of audio from the captain’s and first officer’s audio panel was of fair quality. A summary of the recording was completed.
The seat belt sign was illuminated and the cabin crew was still in the process of preparing the cabin for landing at the time of the event.