# NTSB LAX97LA051: Boeing 737-500, N916UA, Bishop, CA, November 20, 1996 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: November 19, 1996, 17:50 local (Nov 20, 1996, 01:50 UTC) - Place: Bishop, CA - Location: 37.3672° N, 118.3989° W: Placed by OpenAirDocs: center of Bishop, CA, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=37.3672&lon=-118.3989&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 112 uninjured - Status: Completed, report October 14, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 29689 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA051 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29689/pdf - Page: https://openairdocs.org/ntsb/LAX97LA051 ## Probable cause a clear air turbulence encounter. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight encounter with weather, cruise - weather condition - turbulence,clear air (cause) - seat belt sign - selected, pilot in command - seat belt - not used, flight attendant ## Analysis A known area of clear air turbulence was encountered at FL290 shortly after the captain turned on the fasten seat belt sign and instructed the cabin crew to take their seats. An aft flight attendant was in the process of closing a door before she sat down when the aircraft experienced severe turbulence and dropped sharply in altitude. The flight attendant broke her right foot during the encounter and was treated at a local hospital after landing. Company procedures for the crew to follow when turbulence is anticipated is for the flight attendants to take their seats after the cockpit crew makes the announcement and turns on the fasten seat belt sign. The captain had been monitoring the flight conditions of other aircraft at various altitudes in the area and, when turbulence was reported ahead of the flight, he made the announcement. ## Factual narrative On November 19, 1996, at 1750 hours Pacific standard time, a flight attendant sustained a serious foot injury after encountering some clear air turbulence (CAT) near Bishop, California, during cruise at flight level (FL) 290 on United Flight 2188 from San Francisco, California, to Las Vegas, Nevada. The aircraft, a Boeing 737-500, N916UA, was not damaged, nor were there any injuries to the other 112 persons onboard. According to the operator, the captain illuminated the fasten seat belt sign and instructed the flight attendants to take their seats. The injured aft flight attendant was in the process of securing a carrier door in the aft galley when the turbulence was encountered. After arriving in Las Vegas, she was taken to a local hospital where it was determined that her right foot was broken. Another flight attendant stated that shortly after the captain made the announcement, the aircraft dropped sharply. He was holding on to something and didn't get hurt. According to the operator, there were several reports of moderate or greater turbulence throughout central and southern California at flight levels under FL300. A "CAT ALERT" was in effect for the area at the time of the accident with some mention of mountain wave activity east of the Sierra Mountains. This alert was on the Weather Briefing Message (WBM) for Flight 2188. The captain was monitoring the flight conditions of other aircraft in the area and chose the smoother ride at FL290 due to turbulent rides at the higher altitudes. When the captain was advised of turbulent conditions ahead, he made the announcement to the cabin crew to take their seats. United Airlines procedures for crew action to take when turbulence weather conditions are anticipated are to turn on the Fasten Seat Belt sign and make a PA announcement. This permits the flight attendants to tie down serving carts and stow other loose items before taking their seats. If turbulence is encountered unexpectedly, the fasten seat belt sign will be cycled on and off three or four times and a PA announcement advising the passengers and flight attendants to be seated immediately. ## Aircraft - Registration: [N916UA](https://openairdocs.org/deregistered/N916UA-2006-05-22), registration cancelled 2006-05-22, S/N 25383, built 1991 (OpenAirDocs) - Reported make and model: Boeing 737-500 - Registry model: [Boeing 737-522](https://openairdocs.org/model/boeing-737-522) (registry code 138449F) (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: 25383 - Airframe hours: 13535 - Engines: GE CFM56-3-B1 20000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Registered owner: United Airlines - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, July 16, 1996, 1,013 hours before - Departed: SFO, SAN FRANCISCO, CA - Destination: LAS, LAS VEGAS, NV - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 7,857 total ## Weather - Conditions: Visual (VMC), Dusk - Wind: 270° at 55 knots - Lowest ceiling: none - Temperature: -56 °F - Altimeter: 29.00 inHg ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19961119047639A](https://openairdocs.org/incident/19961119047639A), Nov 19, 1996: Boeing 737522, Lasvegas, NV, No damage. (-16) None of the FAA responsibilities were involved. Flight attendant sustained a broken left ankle, 3 broken toes, laceration to neck (12 stitches) and… 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.