United Airlines Flight 870
Boeing 747-422 · Accident: turbulence encounter en route
From Sydney Kingsford Smith International Airport (YSSY) to San Francisco International Airport (SFO)
Event
- NTSB case
- WPR13LA131
- 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
- Unknown
- 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
- N174UA
- Operator
- United Airlines
- Onboard fatalities
- Unknown
- Route
- From Sydney Kingsford Smith International Airport (YSSY), SydneyTo San Francisco International Airport (SFO), 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
- Defining eventThe 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
- Turbulence encounter
- 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
- Environmental issues › Conditions/weather/phenomena
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The flight crew reported that the flight experienced unexpected light-to-moderate turbulence during cruise flight for about 3 hours. The seatbelt sign was illuminated, and the passengers and flight attendants had been seated. A flight attendant, who was on her rest break and was resting in the bunk room, reported that the turbulence had stopped for a while and that she thought she heard a "faint ding" indicating that the seatbelt sign had been turned off, so she went to the lavatory. However, the flight then encountered moderate turbulence, during which the flight attendant sustained a serious injury while walking from her bunk to the lavatory. The flight attendant reported that announcements made over the public address system could not be heard in the bunk room and that it was not always possible to hear when the seatbelt sign was turned on or off. It is likely that, if the flight attendant had a visual indication that the seatbelt sign was on, she would not have attempted to get up until safe movement was assured.
Probable cause
The flight’s encounter with moderate clear air turbulence while en route, which resulted in a serious injury to a flight attendant. Contributing to the accident was the lack of communication equipment in the rest compartment, which, if installed, could have alerted the cabin crewmembers that the seatbelt sign was on.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR13LA131
- Event ID
- 20130220X51849
- Case number
- WPR13LA131
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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: 470a878883a16fd8b789c00eda8da6ba62f4f1967aa1e8a4be86eba9e73fa371; retrieved 2026-09-15T20:58:40.375Z.
- Corrected after a review of the NTSB narrative, which states these values explicitly: destination. Destination label misspells San Francisco (SFO).