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ASN Wikibase Occurrence # 163998
Last updated: 19 November 2021
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Date:17-FEB-2014
Time:12:54
Type:Silhouette image of generic B737 model; specific model in this crash may look slightly different
Boeing 737-724
Owner/operator:United
Registration: N23708
MSN: 28769/52
Fatalities:Fatalities: 0 / Occupants: 120
Other fatalities:0
Aircraft damage: None
Category:Accident
Location:Kaycee, Wyoming -   United States of America
Phase: En route
Nature:Passenger - Scheduled
Departure airport:Denver, CO (KDEN)
Destination airport:Billings, MT (KBIL)
Investigating agency: NTSB
Narrative:
On February 17, 2014, about 1254 mountain standard time (MST), United Airlines flight 1676, a Boeing 737-724, N23708, encountered severe turbulence about flight level 340 near Kaycee, Wyoming. Of the 120 passengers and crew onboard, two flight attendants were seriously injured, and one FA and nine passengers received minor injuries. The airplane was not damaged. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from Denver International Airport (DEN), Denver, Colorado, to Billings Logan International Airport (BIL), Billings, Montana.

The flight departed DEN normally and climbed to a cruising altitude of flight level (FL) 380. The flight encountered light turbulence and the crew requested, and was granted, a descent to FL360 followed by a descent to FL340. The flight crew extinguished the seat belt sign when the ride smoothed out. Flight data recorder (FDR) data indicated the airplane was cruising about FL340 when it encountered an area of severe turbulence for about 55 seconds. The most severe turbulence occurred for about 10 seconds when the vertical acceleration fluctuated between about -1.23 g's and +2.05 g's, the lateral acceleration fluctuated between about -0.27 g's and +0.23 g's, the pitch fluctuated between about +5.8 (nose up) and -1.8 (nose down), and the roll fluctuated between about 14 left and 20 right.


At the time of the turbulence encounter, the two flight attendants (FA) in the forward galley and the one FA in the aft galley were injured. during the turbulence encounter and suffered. The aft FA was unconscious after the event and tended to by medical personnel passengers until landing. After being notified of the serious injuries, the flight crew declared an emergency with air traffic control and arranged for medical personnel to meet the aircraft at BIL. The three FAs were transported to the hospital. One FA was diagnosed with a fractured fibula; one was diagnosed with fractures of her scapula, a rib, cervical vertebrae, and thoracic vertebrae; and one was treated and released with minor injuries.

According to the NTSB weather study, an Airman's Meteorological Information (AIRMET) for moderate turbulence for altitudes between FL270 and FL390 was issued at 0745 MST for a region that included the accident location. The flight dispatch release for the accident aircraft, which included weather information, included a Flight Planning Guidance product from WSI that advised of light/occasional moderate mountain wave activity between FL310 and FL390 close to where the accident occurred.

Probable Cause: an encounter with severe mountain wave turbulence during cruise flight.

Sources:

NTSB
https://flightaware.com/live/flight/UAL1676/history/20140217/1815Z/KDEN/KBIL

NTSB File DCA14LA060

Accident investigation:
cover
  
Investigating agency: NTSB
Status: Investigation completed
Duration: 6 years and 2 months
Download report: Final report
Location


Revision history:

Date/timeContributorUpdates
19-Feb-2014 10:10 whiteshark Added
19-Feb-2014 10:11 harro Updated [Location, Narrative]
19-Feb-2014 17:19 Geno Updated [Time, Other fatalities, Location, Departure airport, Destination airport, Source]
19-Feb-2014 17:22 Geno Updated [Source]
20-Feb-2014 06:20 Whiteshark Updated [Time, Narrative]
03-Mar-2014 16:31 Geno Updated [Time, Phase, Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
03-May-2020 18:58 ASN Update Bot Updated [Time, Operator, Departure airport, Destination airport, Source, Narrative, Accident report, ]
05-May-2021 07:25 goldfish85 Updated [Location, Departure airport, Destination airport, Source, Narrative]
09-May-2021 14:26 harro Updated [Total occupants]

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