Turkish Airlines Flight 634

Turkish Airlines Flight 634 was a scheduled domestic passenger flight from Istanbul Atatürk Airport to Diyarbakır Airport in southeastern Turkey. On 8 January 2003 at 20:19 EET (18:19 UTC), the aircraft operating the flight, a British Aerospace Avro RJ100, struck the ground on final approach approximately 900 m short of the runway threshold during inclement weather conditions. In the following collision with a slope, a post-crash fire broke out, killing 75 of the 80 occupants, including the entire crew. This is the deadliest aviation accident to involve the BAe 146.

Accident

Flight 634 departed Istanbul Atatürk Airport at 18:43 EET (16:43 UTC) for the nearly two-hour flight to Diyarbakır in southeastern Turkey. Approximately one hour into the flight and 40 nmi off the destination airport, the crew contacted Diyarbakir Airport's approach control, which cleared the flight to approach the airport from the south for runway 34 using VHF omnidirectional range – a type of short-range radio navigation system which enables aircraft with a receiving unit to determine their position and stay on course – and instructed the crew to descend to 9000 ft. The weather report relayed to crew by the controller stated no winds and visibility of 3500 m.

When the flight was 8 nmi from runway 34 and at an altitude of 5000 ft, air traffic control instructed the crew to continue the approach and report as soon as they had established visual contact with the runway. The crew acknowledged the call and prepared the aircraft for landing, deploying the landing gear and extending the flaps. Continuing to descend, the aircraft reached its minimum descent altitude (MDA) of 2800 ft – the lowest altitude to which descent is authorized on final approach or during circle-to-land maneuvering in execution of a standard instrument approach procedure where no electronic glideslope is provided (the airport was not equipped with an instrument landing system) – but both pilots said that they still had no visual reference to the runway or its approach lighting system because of the thick fog. One pilot discerned some lights in the distance but was not sure what exactly they belonged to.

Nonetheless, violating standard procedures, the captain decided to continue the approach to as close as 1 mi to the runway and descended further to 500 ft and beyond, well below the MDA. At 1 mi off the threshold of the runway and at an altitude of 200 ft (which in this case constituted the decision height), the ground proximity warning system (GPWS) started to trigger aural alarms. Eight seconds later, the crew decided to abort the landing and initiated a go-around, but before being able to execute the command, the airplane struck the ground with the undersurface of the fuselage and the landing gear at 20:19 EET (18:19 UTC), 900 m off the threshold of runway 34 and 30 m off the approach lights at a speed of around 131 kn.

The aircraft slid on the ground for about 200 m while starting to disintegrate. Eventually, it hit a slope, broke up into three major pieces, exploded and caught fire; most of the bodies and parts of the wreckage were burnt. The debris was spread out in an area of about 800 m2.

The impact instantly killed both pilots, the three flight attendants and 69 of the 75 passengers. Six passengers survived, one of whom however later succumbed to his injuries in hospital.