BBC News | UK | The AAIB interim report

The Air Accident Investigation Branch has published this interim report on the progress of the disaster inquiry thus far:

The Korean Airlines Boeing 747-200 freighter, registration HL 7451, call sign KAL 8509, with three crew and a company ground engineer on board was operating a service from London Stansted to Milan Malpensa.

The aircraft pushed back from stand six at 1813 GMT and was cleared to a taxi at 1826 GMT. The crew were cleared for take off on runway 23 at 1836 GMT.

The weather at the time was rain, surface wind 190/18 kts and a cloud base of 400 to 500 feet.

The take off was observed by Air Traffic Control (ATC) and was reported as normal with the aircraft disappearing from view as it entered cloud.

As the aircraft climbed through 1,400ft the crew were instructed to change frequency to contact London control.

This was acknowledged by the crew and was the last transmission from the aircraft. A short while later an explosion and a fireball were seen approximately one and a half miles south of the airfield.

Realising that the aircraft had crashed, ATC alerted the airport fire and other emergency services.

The aircraft crashed in an area of grassland and pine forest beside a small lake close to some farm buildings. The crew were fatally injured during the impact.

The main structure of the aircraft was totally fragmented. Light debris from the impact explosion, carried aloft by the fireball, was blown by the prevailing south, south-westerly wind and deposited over a large area of the airfield.

An investigation by the AAIB in co-operation with Essex Police began the same evening.

Accredited representatives from the United States and the Republic of Korea together with representatives of the aircraft and engine manufacturers and Korean Air joined the investigation on 23 December.

The cockpit voice recorder was recovered from the wreckage and was successfully replayed at the AAIB headquarters at Farnborough.

The replay indicated that the crew were experiencing problems with the flight instrumentation shortly after take-off.

Work is continuing to further interpret the evidence provided by the cockpit voice recorder.

The flight data recorder has not been found and the search of the accident site continues as a priority task. All four engines have been found at the impact site and the damage to all four is consistent with them running at high power at impact.

Investigation of the wreckage at the scene is ongoing. In the meantime, investigators are examining the recent maintenance history of the aircraft for any relevant defects, rectification or maintenance activity

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