United B752 near San Francisco on Dec 1st 2011, turbulence injures flight attendant

Last Update: October 7, 2015 / 22:16:59 GMT/Zulu time

Bookmark this article

Photo of United N547UA, Boeing 757-200 — United N547UA, Boeing 757-200 (Photo credit: InSapphoWeTrust / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Dec 1, 2011

Classification
Accident

Cause
Turbulence injures flight attendant

Airline
United

Flight number
UA-721

Departure
Denver, United States

Destination
San Francisco, United States

Aircraft Registration
N547UA

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

A United Boeing 757-200, registration N547UA performing flight UA-721 from Denver,CO to San Francisco,CA (USA) with 146 passengers and 5 crew, was on approach to San Francisco descending through FL300 near ELCAP intersection over Yosemite National Park, when the aircraft encountered turbulence causing a serious injury to a flight attendant. The aircraft continued to San Francisco for a safe landing, the flight attendant was taken to a hospital.

The NTSB reported on Dec 17th that the flight attendant suffered a broken fibula.

The NTSB released their final report concluding the probable cause of the accident was:

The flight's encounter with known severe turbulence associated with mountain wave activity, which resulted in a flight attendant sustaining a broken ankle.

The NTSB reported that there were reports of turbulence ahead when the aircraft neared the mountains of the Sierra Nevada. The captain illuminated the fasten seat belt signs and talked to the purser instructing the cabin crew to wrap up cabin service and stay near their seats to immediately take the seats and be belted in upon onset of turbulence. The purser relayed the instructions to the other flight attendants. A flight attendant responsible for the aft galley decided to brush her teeth and went into a lavatory. About 7-10 minutes after the captain had advised the cabin crew the aircraft encountered 2-3 jolts of moderate turbulence followed by severe turbulence. The flight attendant in the lavatory was thrown up against the ceiling twice and back onto the floor landing awkwardly causing the fracture of her right ankle. The aircraft landed in San Francisco 22 minutes later, the flight attendant was taken to a hospital.

The NTSB reported: "The area was favorable for mountain wave activity over the region due to an upper level low, and strong wind flow over the mountain ranges. The GOES-11 visible and infrared satellite images depicted clear skies over the accident area with no visual signs of potential turbulence." and stated: "The FDR data indicated that approximately 1 hour 34 minutes after takeoff, the vertical acceleration fluctuated between 0 g's and 2 g's peaking at a maximum of 1.91 g's during a 28-second time period."