Lauda Air Flight 004

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**Lauda Air Flight 004**
Summary
Date	May 26, 1991
Type	Mechanical Failure
Site	Ban Nong Rong, Thailand
Fatalities	223
Injuries	0
Aircraft
Aircraft type	Boeing B-767-3Z9ER
Operator	Lauda Air
Tail number	OE-LAV
Ship name	Wolfgang Amadeus Mozart
Passengers	213
Crew	10
Survivors	0

Lauda Air Flight 004 was an international passenger flight that crashed due to a thrust reverser deployment of the number 1 engine, in flight.

On May 26, 1991, about 2310 local time, Flight 004 (originating from Hong Kong's Kai Tak Airport), a Boeing B-767-3Z9ER, registration OE-LAV, ship name Wolfgang Amadeus Mozart, took off from Old Bangkok International Airport (now Don Mueang International Airport) for its flight to Vienna International Airport with 213 passengers and 10 crew, under the command of Captain Thomas J. Welch and First Officer Josef Thurner.

At 2322, Welch and Thurner received a visual warning indicating that a possible system failure would cause the thrust reverser on the number 1 engine to deploy in flight. Having consulted the aircraft's Quick Reference Handbook, they determined that it was "just an advisory thing" and took no action.^[1]

At 2331, the thrust reverser on the number 1 engine deployed while the plane was over the jungle near Ban Nong Rong (Uthai Thani Province), Thailand. Thurner's last recorded words were, "Reverser's deployed!".^[2]

The 767 stalled in mid-air and disintegrated at 4000 ft (1200 m). None of the 223 passengers and crew aboard the airliner survived. The accident remains the worst aviation disaster on Thai soil to date.

Upon hearing of the crash, Niki Lauda, retired Formula 1 race driver and owner of the airline, flew to Thailand and personally visited the crash site, turning up information that led to the accident's cause, which was the failure of the thrust reverser isolation valve. He tested his findings in a Boeing 767 simulator in England and revealed those findings in a press conference shortly thereafter.^[3] A subsequent official investigation corroborated Lauda's findings, leading Boeing to modify the thrust reverser system to prevent similar occurrences. Aviation writer Macarthur Job has noted that, "had that Boeing 767 been of an earlier version of the type, fitted with engines that were mechanically rather than electronically controlled, then that accident could not have happened.^[2]