# NTSB CHI97LA292: Boeing 747-422, N175UA, Grand Forks, ND, September 14, 1997 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 14, 1997, 14:24 local (19:24 UTC) - Place: Grand Forks, ND - Coordinates: 47.910572, -97.07093 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.9106&lon=-97.0709&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor, 322 uninjured - Status: Completed, report April 15, 1999 - Report: Approved by Office Director - NTSB case key (mKey): 10701 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI97LA292 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10701/pdf - Page: https://openairdocs.org/ntsb/CHI97LA292 ## Probable cause The flight attendant's seat belt was not secured. A factor was turbulence in the clouds. ## 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 in clouds (contributing factor) - seat belt sign - not followed, flight attendant (cause) - seat belt - not used, flight attendant (cause) ## Analysis Prior to departure, the flight crew received a weather briefing which included a SIGMET for the chance of severe turbulence along the proposed route. Prior to entering IMC conditions, the flight crew turned on the 'Fasten Seat Belt' signs, and gave verbal instructions to passengers to return to their seats and fasten their seat belts. The pilot-in-command diverted around precipitation which he observed on radar; however, when in the close proximity to the precipitation, the airplane encountered what the crew described as three to four seconds of 'moderate' chop. An unseated passenger sustained minor injuries, and a flight attendant received serious injuries. ## Factual narrative On September 14, 1997, at 1424 central daylight time, a Boeing 747-422, N175UA, operating as United Airlines Flight 881, experienced turbulence while in cruise flight near Grand Forks, North Dakota. One flight attendant sustained serious injuries and one passenger received minor injuries. Eighteen cabin attendants and 300 passengers reported no injuries. The airplane received no damage. The international flight departed Chicago, Illinois, at 1302 with the intended destination of Narita, Japan. A Federal Aviation Administration inspector indicated that a SIGMET (43C) was in effect at the time of the accident forecasting the chance of severe turbulence in the area of the encounter. According to written statements, the Captain was at the controls. An area of precipitation was noted on radar which was approximately 50 miles ahead of the airplane. About 15 minutes prior to encountering IMC conditions, the flight crew turned on the "Fasten Seat Belt" signs, and a verbal announcement was made in English and Japanese for the passengers to return to their seats and fasten their seat belts. The statements indicate that the flight deviated to avoid the precipitation; however, the flight was in IMC conditions with continuous light chop. After passing the displayed precipitation, and during a turn back to intercept the original course, the crew reported encountering three to four seconds of "moderate" chop. A few minutes later they were notified by cabin attendants of one passenger injury which occurred which the passenger was not seated. A decision was then made to divert to Minneapolis, Minnesota. The crew stated that they were later informed of an injury sustained by a flight attendant to her knee. After the landing at Minneapolis, it was determined the passenger had received minor injuries; however, the flight attendant's injuries were serious. None of the flight crew reported any injuries. An inspection of the airplane revealed no damage. The flight crew had received a company weather briefing prior to departure from Chicago. SIGMET (43C) which was in effect at the time and indicated the chance of severe turbulence in the area of the turbulence encounter. ## Aircraft - Registration: [N175UA](https://openairdocs.org/deregistered/N175UA-2018-07-30), registration cancelled 2018-07-30, S/N 24382, built 1990 (OpenAirDocs) - Reported make and model: Boeing 747-422 - Registry model: [Boeing 747-422](https://openairdocs.org/model/boeing-747-422) (registry code 1384935) (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: 24382 - Airframe hours: 30275 - Engines: P&W 4056 L 56000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Operator: United Airlines, doing business as United Airlines - Registered owner: Wilmington Trust Company - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, March 22, 1997, 2,132 hours before - Departed: ORD, CHICAGO, IL - Destination: RJAA, NARITA, OF - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; flight engineer, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 20,086 total, 1,660 in this make and model ## Weather - Conditions: Instrument (IMC), Day ## 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 19970914037249A](https://openairdocs.org/incident/19970914037249A), Sep 14, 1997: Boeing 747422, Grand Forks, ND. Encountered severe turbulence near a thunderstorm. Passebgers and flight attendant injured. (.4) on September 14, 1997, at 1424 central daylight time, a Boeing… ## Other investigations on N175UA (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 CHI03IA097](https://openairdocs.org/ntsb/CHI03IA097), Apr 1, 2003: Boeing 747-422 (N175UA), Chicago, IL, incident, no damage. Probable cause: Failure of company maintenance personnel to fully comply with published maintenance/inspection procedures, as well as the resulting inoperative drain heaters and restricted movement of the aileron… 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.