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NTSB Report
December 23, 1988 · Boeing 747SP-21 · N146UA
Midway Islands, PO
Overview
Report Status
Probable Cause
Event Type
Accident
Date
December 23, 1988
Injury Outcomes
2 injuries (1 serious injury, 1 minor injury), 220 uninjured
Location
Midway Islands, PO
Aircraft
Boeing 747SP-21
Tail Number
N146UA
Operator
United Airlines
Injuries
Serious
NTSB Number
LAX89LA068
UNITED AIRLINES FLT 820 WAS ENRTE FROM NORITA, JAPAN TO SAN FRANCISCO, CA. AT FLT LVL 380 SEVERE CLEAR AIR TURBULENCE WAS ENCOUNTERED. THREE CABIN CREW MEMBERS WERE THROWN TO THE CEILING, TWO OF WHOM WERE INJURED, ONE SUSTAINING A FRACTURED LEG. THE FLT DIVERTED TO HONOLULU AND LANDED WITHOUT INCIDENT. BOTH FLT AND CABIN CREW REPORTED THAT THERE HAD BEEN NO WARNING OF ANY IMPENDING TURBULENCE PRIOR TO ABRUPTLY ENCOUNTERING THE TURBULENCE THAT CAUSED THE INJURIES, AND THAT THE SEAT BELT SIGN WAS TURNED OFF.
NTSB Probable Cause
AIRCRAFT'S ENCOUNTER WITH UNFORECAST SEVERVE CLEAR TURBULENCE.
Full Narrative
UNITED AIRLINES FLT 820 WAS ENRTE FROM NORITA, JAPAN TO SAN FRANCISCO, CA. AT FLT LVL 380 SEVERE CLEAR AIR TURBULENCE WAS ENCOUNTERED. THREE CABIN CREW MEMBERS WERE THROWN TO THE CEILING, TWO OF WHOM WERE INJURED, ONE SUSTAINING A FRACTURED LEG. THE FLT DIVERTED TO HONOLULU AND LANDED WITHOUT INCIDENT. BOTH FLT AND CABIN CREW REPORTED THAT THERE HAD BEEN NO WARNING OF ANY IMPENDING TURBULENCE PRIOR TO ABRUPTLY ENCOUNTERING THE TURBULENCE THAT CAUSED THE INJURIES, AND THAT THE SEAT BELT SIGN WAS TURNED OFF.
Flight
Event TypeAccident
Event Time10:30 UTC
Nearest Airport0nm N
Runway0
Flight Plan FiledIFR
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftBoeing 747SP-21
Tail NumberN146UA
Aircraft CategoryAir
OperatorUnited Airlines
Operating RulePart 121
Engines4
Engine TypeTurbofan
Engine DetailsP&W · JT-9D · Turbofan · 40000
Seats331
People & Injuries
Injury Summary2 injuries (1 serious injury, 1 minor injury), 220 uninjured
Fatal0
Serious1
Minor1
Uninjured220
Total222
Crew 1Age 60 · First Class
Conditions
ConditionsUnknown
LightDawn
Wind240°
Visibility50 sm
CeilingNone
Temperature / Dew Point50 / 0 C
Altimeter29.00 inHg
Weather SourcePILO