United Airlines Flight 806
Boeing 747-422 · Accident: in flight encounter with weather en route
From Hong Kong International Airport (VHHH) to San Francisco International Airport (KSFO)
Event
- NTSB case
- LAX96LA013
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Boeing 747-422
- Aircraft type
- Boeing 747
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N191UA
- Operator
- United Airlines
- Onboard fatalities
- Unknown
- Route
- From Hong Kong International Airport (VHHH), Hong KongTo San Francisco International Airport (KSFO), San Francisco, CA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- In flight encounter with weather
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Weather condition › Turbulence, clear air
Not plotted · Location withheld: coordinates are missing, conflicting, invalid, or have no accepted acquisition method. No substitute location has been invented.
NTSB narrative
Six passengers were injured during a severe turbulence encounter over the Pacific Ocean while the aircraft was in cruise at flight level FL330. The accident occurred in international waters near latitude 40 degrees north, longitude 152 degrees east. Review of the forecasts and pilot reports of the dispatch/weather package given to the flight crew prior to departure disclosed that an area of light to moderate turbulence was forecast along the aircraft's planned track from 151 to 162 degrees east longitude. Pilot reports available at the time of departure consistently reported smooth conditions in the area of the forecast turbulence. At the time of the encounter the aircraft was in clear air above a cirrus cloud deck. The crew saw no convective activity ahead either visually or on radar. In the process of preparing for a position report to air traffic control, the flight crew overheard another airline flight ahead of them reporting an encounter with moderate to severe turbulence. The captain decided to secure the cabin as a precaution. The purser was notified of the decision and the captain was in the process of reaching for the seat belt sign when the turbulence was encountered. All of the injured passengers were located aft of row 50, with the majority aft of row 58. None of the injured were secured by seat belts.
Probable cause
an inadvertent encounter with unreported and unforecasted severe turbulence. A factor in the accident was the passengers' non-use of seat belts during cruise flight.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX96LA013
- Event ID
- 20001207X04726
- Case number
- LAX96LA013
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 1dc70019518eaa0cf19f51450dcf287c491842c1b9f60931005ff81351e1ff08; retrieved 2026-09-18T17:57:02.498Z.
- The NTSB's operator name is blank for N191UA; the operator shown is the name the NTSB's other records give its FAA operator code, UALA.