# NTSB CHI03LA237: Boeing B777-222, N779UA, Chicago, IL, July 17, 2003 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: July 17, 2003, 15:45 local (20:45 UTC) - Place: Chicago, IL - Coordinates: 41.979721, -87.904441 - Nearby events: https://openairdocs.org/map.md?lat=41.9797&lon=-87.9044&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 269 uninjured - Status: Completed, report June 2, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 57653 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI03LA237 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/57653/pdf - Page: https://openairdocs.org/ntsb/CHI03LA237 ## Probable cause The turbulence encountered during the descent which seriously injured a passenger returning to her seat after the seat belt sign was activated. A factor was that it was not possible for the returning passenger to comply with the lit seat belt sign. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight encounter with weather, descent - seat belt sign - activated, pilot in command - weather condition - turbulence (cause) - procedures/directives - not possible, passenger (contributing factor) ## Analysis A passenger sustained a broken ankle when the flight encountered moderate turbulence. The captain reported that the seat belt sign was on prior to entering a buildup. The captain stated, "However a passenger, ... had still not taken her seat. Apparently she had been in the lavatory when I turned on the seat belt sign, and was returning to her seat at the time of the encounter." An excerpt from an airline weather study stated, "Even though the main band of convective activity had passed the location of the incident, the possibility of a towering cumulus cell re-building behind the first band was indeed possible as the air mass was becoming gradually unstable again. ... Therefore, the pilot report of encountering a jolt of light turbulence followed by moderate turbulence is plausible." ## Factual narrative On July 17, 2003, about 1545 central daylight time a Boeing 777-222, N779UA, operated as United Airlines flight 958 from Denver to Chicago, piloted by an airline transport rated captain and first officer, sustained a serious in-flight injury to one passenger when the flight encountered moderate turbulence near Beloit, Wisconsin. The 14 CFR Part 121 scheduled domestic passenger flight was operating on an IFR flight plan. Visual meteorological conditions prevailed at the time of the accident. The 2 flight crewmembers, 10 cabin crewmembers and the remaining 257 passengers were uninjured. The flight originated from Denver International Airport, Denver, Colorado, about 1300 mountain daylight time and was en route to Chicago O'Hare International Airport (ORD), Chicago, Illinois at the time of the accident. The flight landed at ORD at 1556. The operator forwarded a copy of the captain's statement. The statement said: On descent into ORD, approaching from the west, about 2 minutes after the seat belt sign had been turned on, we penetrated a small buildup that was difficult to avoid due to other weather and [Air Traffic Control] constraints. We were painting extensive, very threatening convective weather to the north and east of the airport, but the cell we penetrated didn't even show on the radar. We encountered a jolt of light turbulence, followed by a jolt of moderate turbulence, total encounter about 5 seconds. My immediate concern was for my flight attendants since I hadn't had time to warn them. They were all OK, however a passenger, a woman approximately 70 years old, ... had still not taken her seat. Apparently she had been in the lavatory when I turned on the seat belt sign, and was returning to her seat at the time of the encounter. She suffered a badly broken ankle. United Airlines provided a weather study, which is appended to the docket material associated with this case. An excerpt from that study stated: Even though the main band of convective activity had passed the location of the incident, the possibility of a towering cumulus cell re-building behind the first band was indeed possible as the airmass was becoming gradually unstable again. The cold front east-west over southern Wisconsin did not pass the IL/WI border until 2230UTC. As a result, there was time for cumulus and towering cumulus to re-develop over the area. Therefore, the pilot report of encountering a jolt of light turbulence followed by moderate turbulence is plausible. ## Aircraft - Registration: [N779UA](https://openairdocs.org/aircraft/N779UA), registered now, S/N 26941, built 1996 (OpenAirDocs) - Reported make and model: Boeing B777-222 - Registry model: [Boeing 777-222](https://openairdocs.org/model/boeing-777-222) (registry code 1385219) (OpenAirDocs) - Registry engine: [Pratt & Whitney PW4000 series](https://openairdocs.org/engine/pratt-whitney-pw4000-series) (registry code 52119, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 26941 - Airframe hours: 28617 - Engines: Pratt & Whitney PW4077 77000 lbs thrust turbo fan; Pratt & Whitney PW4077 77000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Registered owner: United Air Lines Inc - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, September 23, 2002, 3,115 hours before - Departed: DEN, DENVER, CO - Destination: ORD, CHICAGO, IL - Flight plan: IFR - Airport: ORD, Chicago O'Hare Intl ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 58; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review January 1, 2003; seat: left; flight hours: 13,014 total, 1,681 in this make and model, 220 in the last 90 days, 92 in the last 30 days, 27 in the last 24 hours - Co-pilot; age 40; injuries: none; airline transport, flight engineer; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review May 1, 2003; seat: right; flight hours: 6,840 total, 1,970 in this make and model, 46 in the last 90 days, 46 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 210° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: 6,000 ft broken - Temperature: 84 °F, dew point 68 °F - Altimeter: 30.04 inHg - Observed at: ORD, 57 nm away ## 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 20030717021539A](https://openairdocs.org/incident/20030717021539A), Jul 17, 2003: Boeing 777222, Chicago, IL. (-23) On descent into ord, the flight encountered a brief period of moderate turbulence. A passenger who was returning to her seat suffered a badly broken… 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.