Lauda Air Flight 004

Lauda Air Flight 004

OE-LAV the Lauda Air Boeing 767-300ER aircraft involved in the accident.
Accident summary
Date	26 May 1991
Summary	In-flight breakup caused by uncommanded thrust reverser deployment
Site	Phu Toei National Park, Amphoe Dan Chang, Suphanburi Province, Thailand
Passengers	213
Crew	10
Fatalities	223 (all)
Survivors	0
Aircraft type	Boeing 767-3Z9ER
Aircraft name	Mozart
Operator	Lauda Air
Registration	OE-LAV
Flight origin	Kai Tak Airport, Hong Kong
Last stopover	Don Mueang International Airport, Bangkok, Thailand
Destination	Vienna International Airport, Vienna, Austria

Lauda Air Flight 004 was an international passenger flight of a Boeing 767-300ER that crashed on 26 May 1991 due to an uncommanded thrust reverser deployment of the No.1 engine in mid-flight, killing all 213 passengers and the 10 crew members on board. To date, it remains the deadliest aviation accident involving a Boeing 767 and the deadliest aviation accident in Thailand. The crash also marked the aircraft type's first fatal incident and first hull loss.Lauda Air was founded and run by the former Formula One world motor racing champion Niki Lauda. Lauda was personally involved in the accident investigation.

The aircraft involved was a Boeing 767-300ER which had been delivered new to Lauda Air on 16 October 1989 and was only ever operated by them. It wore the manufacturing number MSN 24628, was registered as OE-LAV and was christened Mozart.

At the time of the accident, Lauda Air operated three weekly flights between Bangkok and Vienna. On 26 May 1991, at 23:02 local time, flight NG004 (originating from Hong Kong's Kai Tak Airport), a Boeing 767-3Z9ER, took off from Old Bangkok International Airport (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 of the United States and First Officer Josef Thurner of Austria.

At 23:08, Welch and Thurner received a visual warning indicating that a possible system failure would cause the thrust reverser on the number one 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.

At 23:17, the thrust reverser on the number one engine deployed while the plane was over mountainous jungle terrain in the border area between Suphanburi and Uthai Thani provinces in Thailand. Thurner's last recorded words were, "Oh, reverser's deployed." The lift on the aircraft's left side was disrupted due to the reverser deployment, and the aircraft was placed in an immediate diving left turn. The aircraft went into a diving speed of Mach 0.99, and may have broken the sound barrier. The aircraft broke up in mid-air on the way down at 4,000 feet (1,200 meters). Most of the wreckage was scattered over a remote forest area roughly 1 km² in size, at an elevation of 600 m above sea level, in what is now Phu Toei National Park, Suphanburi. The wreckage site is about 6 kilometres (3 nmi) north northeast of Phu Toey, Huay Kamin, Dan Chang District, Suphan Buri Province, about 160 kilometres (100 mi) northwest of Bangkok, close to the Burma-Thailand border.