1976 Zagreb mid-air collision

plane2_origin = Split Airport Split, Yugoslavia
plane2_destination = Cologne Bonn Airport Cologne, West Germany
plane2_passengers = 108
plane2_crew = 5
plane2_survivors = 0

The 1976 Zagreb mid-air collision occurred on 10 September 1976 when British Airways Flight 476, a Hawker Siddeley Trident 3B en route from London Heathrow Airport to Yeşilköy International Airport, Istanbul, collided in mid-air with Inex-Adria Aviopromet Flight 550, a Douglas DC-9 en route from Split Airport, Yugoslavia, to Cologne Bonn Airport, West Germany, at 10:14 UTC. All 176 people aboard both flights were killed. The disaster is one of only two British Airways flights involving loss of life (the other being British Airways Flight 149, where one person was executed several hours after the Iraqi invasion of Kuwait).

Introduction

In the mid-1970s, the Zagreb air traffic control region was one of the busiest in Europe despite being seriously undermanned and poorly equipped. The Zagreb VOR was a reporting point for a number of congested airways between northern Europe and southeastern Europe, the Middle East, and beyond. The airspace was divided into three sectors by altitude: the lower sector below 24,000 feet, the middle sector from 24,000 to 31,000 feet, and the upper sector above 31,000 feet.

British Airways Flight 476

British Airways Flight 476 departed Heathrow at 08:32 UTC as flight BEA476. At the controls of the Trident 3B was experienced captain Dennis Tann (born 21 June 1932), who by the time of the accident had accumulated 10,781 flying hours. He was assisted by first officer Brian Helm and acting first officer Martin Flint. The flight was uneventful until the aircraft reached the Zagreb VOR.

Inex-Adria Aviopromet Flight 550

Inex-Adria Flight 550 departed Split, Yugoslavia at 09:48 UTC bound for Cologne, West Germany as flight JP550. At the controls sat captain Jože Krumpak and first officer Dušan Ivanuš.

Air traffic controllers

At the time of the accident there were five controllers (and chief of shift) in Zagreb Area Control Center:

* Julio Dajčić, chief of shift (born 17 December 1932)
* Gradimir Tasić (born 29 April 1949), upper sector controller (at the time of the accident)
* Nenad Tepeš (born 2 September 1943), upper sector controller
* Mladen Hochberger (born 13 October 1946), upper sector controller
* Bojan Erjavec (born 15 June 1947), middle sector controller
* Gradimir Pelin (born 18 April 1948), middle sector controller

The accident

Flight 476 established contact with the Zagreb ACC upper sector controller Gradimir Tasić on 134.45 MHz at 10:04:12 UTC:

As Tasić watched his screen, he saw the two paints merge, pass for a moment, and then vanish. He called out to BEA476 and asked it to report passing the next waypoint at Našice:

Tasić continued to call the two aircraft, ignoring calls from other aircraft:

The two aircraft had collided over the town of Vrbovec. The last 5 meters of the DC-9's left wing sliced through the Trident's cockpit section. The DC-9 went into an immediate nose dive; the Trident remained in flight for a short while before going down. All 63 people aboard flight 476 and 113 people aboard flight 550 were killed.

Trial

By noon that day, all controllers were in custody for interrogation. Later, all were released except Tasić, who remained in custody until the trial.

The trial opened on 11 April 1977 in Zagreb District Court. All the controllers were indicted under the Penal Code of Yugoslavia, Articles 271-72 as "persons who by endangering railway, sea or air traffic, threaten the lives of men or property".

Tasić was the only one to be found guilty; he was sentenced to seven years' imprisonment. After a petition by air traffic controllers, it was determined that Tasić had been used as a scapegoat, and he was released on 29 November 1978. He had served over two years and three months in prison.

References

* Richard Weston and Ronald Hurst, "Zagreb One Four: Cleared to Collide?", 1982 (ISBN 0-246-11185-2)
* AAIB, "British Airways Trident G-AWZT, Inex-Adria DC-9 YU-AJR: Report on the collision in the Zagreb area, Yugoslavia, on 10 September 1976" (Reprint of the report produced by The Yugoslav Federal Civil Aviation Administration Aircraft Accident Investigation Commission), Aircraft Accident Report 5/77
* AAIB, "British Airways Trident G-AWZT, Inex-Adria DC-9 YU-AJR: Report on the collision in the Zagreb area, Yugoslavia, on 10 September 1976" (Reprint of the report produced by The Yugoslav Federal Committee for Transportation and Communications - Second Commission of Inquiry with United Kingdom Addendum), Aircraft Accident Report 9/82

External links

* [http://www.airdisaster.com/special/special-bea476.shtml AirDisaster.com report on Zagreb collision]
* [http://aviation-safety.net/database/record.php?id=19760910-0 Aviation Safety Network report on British Airways Flight 476]
* [http://aviation-safety.net/database/record.php?id=19760910-1 Aviation Safety Network report on Inex-Adria Avropromet Flight 550]
* [http://www.airliners.net/search/photo.search?front=yes&s=1&keywords=G-AWZT Pre-collision photos of two aircraft taken from Airliners.net]