Turkish Airlines Flight 278, operated by a Boeing 737-4Y0 registered TC-JES and named Mersin, was a domestic scheduled flight from Ankara Esenboğa Airport to Van Ferit Melen Airport in eastern Turkey that crashed on 29 December 1994 during its final approach to land in driving snow. Five of the seven crew and 52 of the 69 passengers lost their lives, while two crew members and 17 passengers survived with serious injuries.

The aircraft, a Boeing 737-400 with two CFMI CFM56-3C1 jet engines, was built by Boeing with manufacturer serial number 26074/2376, and made its first flight on 25 September 1992. The captain was Adem Ungun, and the first officer was Yavuz Alıcı.

At 15:30 EET (13:30 UTC), the plane struck a hill near Edremit district of Van Province at 1,700 m (5,700 ft) above mean sea level around 4 km (2.5 mi) from Van Airport while on a third VOR-DME approach to the Runway 03 in bad weather, despite a warning from air traffic control not to attempt any more approaches in a snowstorm. The visibility was 900 m (3,000 ft) reducing to 300 m (980 ft) in heavy driving snow.

It was the deadliest aviation accident involving a Boeing 737-400 at that time. It was subsequently surpassed by Adam Air Flight 574 which crashed on 1 January 2007 with 102 fatalities, and fourth deadliest aircraft accident in Turkey at that time.

The aircraft had a crew of 7 and 69 passengers including two babies. Two of the crew and 17 passengers survived the crash with serious injuries.

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