Incident Overview
On 15 April 2012, at approximately 0549 coordinated universal time, US Airways flight 496, an Airbus A319-132 with registration N808AW, was operating as a scheduled passenger flight under 14 CFR Part 121 from Phoenix Sky Harbor International Airport (KPHX), Phoenix, Arizona, to Denver International Airport (KDEN), Denver, Colorado. The aircraft carried 98 passengers and crew. While at flight level 320 in the vicinity of Buena Vista, Colorado, the airplane encountered severe mountain wave turbulence.
Crew Actions and Aircraft Response
According to the operator, the captain was the pilot monitoring and the first officer (FO) was the pilot flying. The flight had been cleared to descend from FL390 to 17,000 feet. The seatbelt sign was on during the descent, and no pilot reports of turbulence had been issued for the area. The captain activated the weather radar and observed no returns between the aircraft and the destination. As the airplane descended through approximately FL320, the captain noted a rapid increase in airspeed. He disconnected the autopilot, simultaneously informing the FO of the overspeed condition, and initiated a nose-up input. The FO also began commanding a nose-up input, at which point the captain released his pitch input. The crew received an overspeed warning, followed by the onset of severe turbulence. The flight crew reported that the encounter lasted approximately 10 to 15 seconds. Afterward, both Elevator and Aileron Computers (ELAC) displayed faults. The FO resumed pilot flying duties while the captain executed procedures to reset ELAC 1 and 2, reported the encounter to air traffic control and dispatch, and contacted the flight attendants.
Injuries and Passenger Details
The A flight attendant (A-FA) was seated in the forward jumpseat. The B flight attendant (B-FA) and C flight attendant (C-FA) were in the aft galley, sitting in their jumpseats without their seatbelts fastened. During the turbulence, both aft flight attendants were thrown upward, striking the overhead ceiling panels before falling to the floor. Two passengers who were also not wearing seatbelts were lifted from their seats and struck ceiling panels. The turbulence caused oxygen masks to deploy in several rows of seats. Two onboard medical personnel, with assistance from the A-FA, tended to the B-FA and C-FA.
Post-Event Response
The captain declared a medical emergency and arranged for emergency personnel to meet the flight upon arrival. At the gate, paramedics transported the two injured flight attendants and one injured passenger to the hospital.
Injuries
Two flight attendants sustained serious injuries, and one passenger sustained minor injuries.