- Date
- October 24, 1991, 14:00 local (20:00 UTC)
- Place
- Denver, CO
- Injuries
- 280 uninjured
- Damage
- No damage
- Phase of flight
- Enroute
- Aircraft
- N4719UBoeing 747-122
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 5, 1993
- Report
- Approved by Office Director
- FAA report
- 19911024057319I
- Case key
- 18164
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.
On this page
Probable cause
The NTSB’s determination of the probable cause, and any contributing factors.
A malfunction in the stabilizer trim control module.
Analysis
During level off at flight level 290, while on a scheduled international passenger flight from san francisco, California, to london, england, elevator pitch control became erratic and oscillations of up to 1,000 feet either side of the base altitude occurred. The auto pilot was disconnected, communications with maintenance control was held, and the flight proceeded to the nearest airport with runways exceeding 10,000 feet in length. An uneventful precautionary landing was conducted in Denver, Colorado. Stabilizer trim components were examined revealing discrepencies in the trim module and elevator feel computer, due to normal wear.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Aircraft
- Registration
- N4719U
- Reported as
- Boeing 747-122
- Category
- Airplane
- Serial number
- 8019
- Engine
- P&W JT9D, 45,800 lbs thrust, turbo fan
- Damage
- No damage
- Flight
- Part 121
- Operator
- United Airlines
- Registered owner
- United Airlines
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · January 2, 2000
- Departed
- SFO · San Francisco, CA
- Destination
- LHR · London
- Flight plan
- IFR
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Certificate
- Airline transport
- Airplane ratings
- Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Unknown, Unknown
- Seat
- Left
- Flight hours
- 25,000 total
Weather
- Conditions
- Visual (VMC) · Day
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.