# NTSB DCA14LA060: Boeing 737, N23708, Kaycee, WY, February 17, 2014 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: February 17, 2014, 12:54 local (19:54 UTC) - Place: Kaycee, WY - Coordinates: 43.722221, -106.964164 - Nearby events: https://openairdocs.org/map.md?lat=43.7222&lon=-106.9642&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Turbulence encounter](https://openairdocs.org/ntsb-events/360) - Highest injury: Serious injuries - Injuries: 2 serious, 10 minor, 108 uninjured - Status: Completed, report April 22, 2020 - Report: Approved by Office Director - NTSB office: Major Investigations Division - Parties: Federal Aviation Administration - NTSB case key (mKey): 88794 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA14LA060 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/88794/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=88794 - Page: https://openairdocs.org/ntsb/DCA14LA060 ## Probable cause an encounter with severe mountain wave turbulence during cruise flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Turbulence: convective turbulence](https://openairdocs.org/ntsb-findings/03032020): Environmental issues › Conditions/weather/phenomena · Effect on personnel (probable cause); cases with it: [Boeing 737-724, 1 case](https://openairdocs.org/ntsb-findings/03032020/cases.md?model=13844BY), [All aircraft, 145 cases](https://openairdocs.org/ntsb-findings/03032020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Turbulence encounter](https://openairdocs.org/ntsb-events/360) (defining event); cases with it: [Boeing 737-724, 3 cases](https://openairdocs.org/ntsb-events/360/sequence.md?model=13844BY), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md) ## Analysis The flight departed normally and climbed to its cruising altitude where it encountered light turbulence. The flight crew descended to a lower altitude twice in an effort to find a smooth ride. The flight encountered an area of severe mountain wave turbulence when the flight was cruising at flight level (FL) 340 in smooth air with the seat belt sign off seriously injuring two flight attendants. 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. ## Factual 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. ## Aircraft - Registration: [N23708](https://openairdocs.org/aircraft/N23708), registered now, S/N 28769, built 1998 (OpenAirDocs) - Reported make and model: BOEING 737 (724) - Registry model: [Boeing 737-724](https://openairdocs.org/model/boeing-737-724) (registry code 13844BY) (OpenAirDocs) - Registry engine: [CFM International CFM56 series](https://openairdocs.org/engine/cfm-international-cfm56-series) (registry code 13802, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 28769 - Year built: 1998 - Airframe hours: 52012 - Engines: CFM INTL. CFM56 SERIES turbo fan; CFM INTL. CFM56 SERIES turbo fan - Damage: No damage - Flight: Part 121 - Operator: Continental Airlines, doing business as United - Registered owner: Wells Fargo Bank Northwest Na Trustee - Airworthiness certificate: Standard, Transport - Departed: DEN, DENVER, CO - Destination: BIL, BILLINGS, MT - Flight plan: IFR - Equipment: Electronic multifunction display, Data recorder, Auto-pilot, Angle of attack indicator, Stall warning system, Onboard weather ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 7, 2013; seat: left; restraint: 5-point; flight hours: 18,300 total, 7,000 in this make and model, 12,000 as pilot in command, 220 in the last 90 days, 75 in the last 30 days, 0 in the last 24 hours - Co-pilot; age 46; injuries: none; commercial, airline transport, private, flight instructor, military; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review October 13, 2013; seat: right; restraint: lap only; flight hours: 5,200 total, 800 in this make and model, 3,400 as pilot in command, 150 in the last 90 days, 46 in the last 30 days - Cabin crew; injuries: serious - Cabin crew; injuries: serious - Cabin crew; injuries: minor ## Weather - Conditions: Not reported ## Other investigations on N23708 (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB DCA16CA181](https://openairdocs.org/ntsb/DCA16CA181), Mar 15, 2016: Boeing 737 724 (N23708), Port Arthur, TX, no damage. Probable cause: an inadvertent encounter with clear air turbulence. ## Docket (12 files) The files NTSB released with the investigation on May 12, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=88794. 24.1 MB in all. - Flight Data Recorder Specialist's Factual Report (item 1, .PDF, 221 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483640&FileExtension=.PDF&FileName=Flight%20Data%20Recorder%20Specialist%27s%20Factual%20Report-Master.PDF - Flight Data Recorder Specialist's Factual Report - Attachment 1 (item 2, .CSV, 17.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483641&FileExtension=.csv&FileName=Flight%20Data%20Recorder%20Specialist%27s%20Factual%20Report%20-%20Attachment%201-Master.csv - Weather Study (item 3, .PDF, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483642&FileExtension=.PDF&FileName=Weather%20Study-Master.PDF - Attachment 1 to the Weather Study (item 4, .PDF, 305 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483643&FileExtension=.PDF&FileName=Attachment%201%20to%20the%20Weather%20Study-Master.PDF - Air Traffic Control Radar Source Data Part 1 (item 5, .PDF, 80 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483644&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20Radar%20Source%20Data%20Part%201-Master.PDF - Air Traffic Control Radar Source Data Part 2 (item 6, .PDF, 55 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483645&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20Radar%20Source%20Data%20Part%202-Master.PDF - Air Traffic Control CZI PIREP 17 Feb (item 7, .PDF, 118 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483648&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20CZI%20PIREP%2017%20Feb-Master.PDF - Air Traffic Control MOR (item 8, .PDF, 16 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483649&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20MOR-Master.PDF - Air Traffic Control AIRMET METARS (item 9, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483650&FileExtension=.PDF&FileName=Air%20Traffic%20Control%20AIRMET%20METARS-Master.PDF - Crew Statements (item 10, .PDF, 116 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483651&FileExtension=.PDF&FileName=Crew%20Statements-Master.PDF - Cockpit Voice Recorder - Factual Report (item 11, .PDF, 231 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483652&FileExtension=.PDF&FileName=Cockpit%20Voice%20Recorder%20-%20Factual%20Report-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 12, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483653&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.