Narrative:Flight BA475 (a HS-121 Trident) took from London-Heathrow at 08:32 GMT for a flight to Istanbul. About 1½ hours later, the aircraft approached the ZAG VOR beacon on airway UB5 at FL330 (10000m), heading 116° (speed 905km/h).
|Date:||Friday 10 September 1976|
|Type:||Hawker Siddeley HS-121 Trident 3B|
|C/n / msn:|| 2320|
|First flight:|| 1972|
|Total airframe hrs:||8627|
|Engines:|| 3 Rolls Royce 512-5W Spey|
|Crew:||Fatalities: 9 / Occupants: 9|
|Passengers:||Fatalities: 54 / Occupants: 54|
|Total:||Fatalities: 63 / Occupants: 63 |
|Collision casualties:||Fatalities: 113|
|Airplane damage:|| Damaged beyond repair|
|Location:||near Vrbovec ( Croatia)
|Phase:|| En route (ENR)|
|Nature:||International Scheduled Passenger|
|Departure airport:||London-Heathrow Airport (LHR/EGLL), United Kingdom|
|Destination airport:||Istanbul-Yesilköy Airport (IST/LTBA), Turkey|
At the same time the Inex Adria DC-9-31 also approached the ZAG VOR, but flew airway UB9, climbing from FL260 to FL350. The DC-9 had taken off from Split at 09:48 GMT for a flight to Köln.
At 10:14:14 the DC-9 captain radioed that they were climbing through FL325. According to ATC data the Flight BA475 was approaching ZAG VOR at FL335 (FL330 actually). Zagreb ATC asked (in Serbo-Croatian) the Inex flight to maintain their present altitude. At 10:14:38 the crew of flight JP550 replied (also in Serbo-Croatian) that they where maintaining FL330.
Three seconds afterwards the outer five meters of the DC-9's left wing cut through the Trident's cockpit.
Due to the sudden decompression, the forward part of the Trident's fuselage disintegrated. The remaining part of the fuselage struck the ground tail-first and slid some 4-5m. to the left.
With it's left wing torn off, the DC-9 tumbled down and hit the ground right-wing first.
CAUSES OF THE ACCIDENT: "1) Direct cause of the accident was the struck of the DC-9 wing into the middle side of the TRIDENT THREE fuselage which occurred at the height of 33.000 feet above Zagreb VOR so that both aircraft became uncontrollable and fell on the ground.; 2) Improper ATC operation; 3) Non-compliance with regulations on continuous listening to the appropriate radio frequency of ATC and non-performance of look-out duty from the cockpits of either aircraft."
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» Aviation Week & Space Technology
» Collision course / by Tony Brkic
Official accident investigation report
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not
display the exact flight path.
Distance from London-Heathrow Airport to Istanbul-Yesilköy Airport as the crow flies is 2495 km (1560 miles).