# NTSB ATL91LA091: Boeing B767-287ER, N651US, Memphis, TN, May 4, 1991

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: May 4, 1991, 17:40 local (22:40 UTC)
- Place: Memphis, TN
- Coordinates: 35.169921, -89.859977 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.1699&lon=-89.8600&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 11 minor, 104 uninjured
- Status: Completed, report February 12, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8402
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL91LA091
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8402/pdf
- Page: https://openairdocs.org/ntsb/ATL91LA091

## Probable cause

THE DELAYED INFLIGHT DECISION BY THE PILOT TO MANEUVER THE AIRCRAFT AWAY FROM THUNDERSTORM ACTIVITY.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight encounter with weather, cruise - normal
  - weather condition - turbulence(thunderstorms) (contributing factor)
  - in-flight planning/decision - delayed, pilot in command (cause)
- Altitude deviation,uncontrolled, cruise - normal

## Analysis

THE FLIGHT WAS IN LEVEL CRUISE FLIGHT AT FL430. THERE WAS SIGNIFICANT LEVEL 6 THUNDERSTOM ACTIVITY IN THE IMMEDIATE VICINITY OF THE TOLSA VOR AT THE TIME OF THE ACCIDENT, AND SIGMETS HAD BEEN ISSUED TO AND RECEIVED BY THE FLIGHT CREW ADVISING OF THIS ACTIVITY. THE FLIGHT CREW STATED THAT THE ONLY WEATHER BEING DEPICTED BY THEIR ON BOARD WEATHER RADAR WAS 40 MILES FROM THEIR POSITION AT THE TIME OF THE ACCIDENT AND NOT IN THEIR FLIGHT PATH. ACCORDING TO TRANSCRIPTS OF THEIR CONVERSATION WITH AIR TRAFFIC CONTROL PERSONNEL, APPROXIMATELY FIVE MILES WEST OF THE TULSA VOR AND TWO MINUTES PRIOR TO THE ACCIDENT, THE FLIGHT CREW REQUESTED AND RECEIVED PERMISSION TO DEVIATE FROM THE ASSIGNED COURSE IN ORDER TO AVOID BUILDUPS IN THEIR FLIGHT PATH. THE FLIGHT ENCOUNTERED SEVERE TURBULENCE FOR A PERIOD OF ABOUT 10 TO 20 SECONDS. THE AIRCRAFT DESCENDED 3500 FEET BEFORE THE FLIGHT CREW WAS ABLE TO REGAIN CONTROL OF THE AIRCRAFT'S DESCENT. THE FLIGHT THEN DIVERTED TO MEMPHIS, TENNESSEE IN ORDER TO OBGAIN MEDICAL ATTENTION FOR THOSE PERSONS INJURED IN THE CABIN SECTION OF THE AIRCRAFT.

## Aircraft

- Registration: N651US (not matched to a registry record)
- Reported make and model: BOEING B767-287ER
- Category: Airplane
- Serial number: 24764
- Engines: GE CF6-80C2-B2 49140 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: Usair
- Registered owner: Usair
- Departed: LAX, LOS ANGELES, CA
- Destination: CLT, CHARLOTTE, NC
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; flight hours: 18,500 total, 1,000 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 240° at 15 knots, gusting 30
- Visibility: 7 statute miles
- Lowest ceiling: 2,500 ft overcast
- Temperature: 70 °F, dew point 66 °F
- Altimeter: 29.00 inHg
- Observed at: TUL, 5 nm away

## 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 19910504062889A](https://openairdocs.org/incident/19910504062889A), May 4, 1991: Boeing 767200, Memphis, TN. Severe turbulence at FL450. Rain,hail and thunderstorm in area. Passengers and flight attendent injured.

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.

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