Accident Boeing 777-224ER N79011,
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ASN Wikibase Occurrence # 309736
 
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Date:Tuesday 21 March 2023
Time:15:23 LT
Type:Silhouette image of generic B772 model; specific model in this crash may look slightly different    
Boeing 777-224ER
Owner/operator:United Airlines
Registration: N79011
MSN: 29859/227
Year of manufacture:1999
Total airframe hrs:101792 hours
Engine model:GE GE90-90B
Fatalities:Fatalities: 0 / Occupants: 192
Aircraft damage: None
Category:Accident
Location:near San Francisco International Airport, CA (SFO/KSFO) -   United States of America
Phase: En route
Nature:Passenger - Scheduled
Departure airport:San Francisco International Airport, CA (SFO/KSFO)
Destination airport:München-Franz Josef Strauss Airport (MUC/EDDM)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
United Airlines flight UA194 encountered convective turbulence while climbing through 19,000 ft after departure from San Francisco International Airport (SFO), San Francisco, CA, and a flight attendant was seriously injured. Upon being notified of the injury, the flight crew declared an emergency and diverted to Denver, Colorado for medical assistance.
The flight crew reported that before departure, the purser (lead flight attendant) was asked to have the flight attendants remain seated until the 10,000 ft signal due to weather conditions at the departure airport. After departure, airspeed fluctuations and turbulence were encountered with a smooth ride once the airplane was above a cloud layer. About 12,000 ft the captain gave the 10,000 ft signal that it was safe for the flight attendants to begin the initial service.
When the flight was about 32 miles northeast of SFO the flight crew established communication with Oakland Air Route Traffic Control Center (ARTCC) while climbing through flight level (FL) 175 [17,500 ft]. The controller advised them to expect occasional light turbulence up to FL 260 and instructed them to climb to FL350.
Shortly thereafter, as the airplane climbed through 19,000 ft, the flight encountered unexpected turbulence for about 5 seconds. The flight crew then received a call from the cabin advising them that a flight attendant had fractured her leg.
At the time of the turbulence event, one of the flight attendants was in the aft galley preparing her cart for the initial service when she felt “violent up and down jolting turbulence'. She attempted to move towards the nearest jump seat when another “intense bump' occurred. She was thrown into the air and impacted the floor fracturing her leg.
Airmen's Meteorological Information (AIRMETs) were in effect at the time of the accident for moderate turbulence below 12,000 ft and moderate turbulence from FL220 to FL360. A convective Significant Meteorological Information (SIGMET) was issued at 1455 PDT and in effect at the time of the accident for the area with areas of thunderstorms forecast with tops to FL290. A convective SIGMET implies severe or greater turbulence, severe icing, and low-level windshear. Numerous pilot reports (PIREPs) reporting moderate or greater turbulence were issued for central California (including the accident area) within two hours of the accident time.

Probable Cause: An encounter with forecast convective turbulence during climb.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: DCA23LA213
Status: Investigation completed
Duration: 3 months
Download report: Final report

Sources:

NTSB DCA23LA213

Location

Revision history:

Date/timeContributorUpdates
25-Mar-2023 19:15 harro Added
25-Jun-2023 19:42 ASN Update Bot Updated
25-Jun-2023 19:44 harro Updated

Corrections or additions? ... Edit this accident description

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