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ASN Wikibase Occurrence # 140481
Last updated: 15 October 2021
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Type:Silhouette image of generic B752 model; specific model in this crash may look slightly different
Boeing 757-222
Owner/operator:United Airlines
Registration: N547UA
MSN: 25368/414
Fatalities:Fatalities: 0 / Occupants: 152
Aircraft damage: None
Location:Modesto Three STAR, ELCAP intersection, Yosemite Nat\'l Park, CA -   United States of America
Phase: Approach
Nature:Passenger - Scheduled
Departure airport:Denver, CO (DEN)
Destination airport:San Francisco, CA (SFO)
Investigating agency: NTSB
While en route at flight level (FL) 360, the captain of the commercial air carrier flight requested and was granted a lower altitude (FL 300) to minimize the effect that turbulence was having on the airplane. After the captain received pilot reports indicating that varying degrees of turbulence, mountain wave activity, and low-level windshear existed, he illuminated the seat belt sign and made an announcement for the passengers to be seated. The flight crew then advised the cabin crewmembers of possible turbulence and instructed them to prepare the cabin for landing, stay near their seats, and be seated immediately if turbulence was encountered. About 7 to 10 minutes later, while the airplane was at FL 300, the flight encountered moderate-to-severe turbulence. A flight attendant who was in the lavatory when the turbulence was encountered sustained a broken ankle after being thrown in the air twice.
Probable Cause: The flight's encounter with known severe turbulence associated with mountain wave activity, which resulted in a flight attendant sustaining a broken ankle.



Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 3 years and 8 months
Download report: Final report


Photo of N547UA courtesy

Tampa - International (KTPA / TPA)
25 August 1993; (c) Freek Blokzijl

Revision history:

19-Dec-2011 09:12 Geno Added
21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Nov-2017 17:39 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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