Accident description
Last updated: 21 September 2014
Status:Final
Date:Friday 10 September 1976
Time:10:14
Type:Hawker Siddeley HS-121 Trident 3B
Operator:British Airways
Registration: G-AWZT
C/n / msn: 2320
First flight: 1972
Total airframe hrs:8627
Cycles:6952
Engines: 3 Rolls-Royce Spey 512-5W
Crew:Fatalities: 9 / Occupants: 9
Passengers:Fatalities: 54 / Occupants: 54
Total:Fatalities: 63 / Occupants: 63
Collision casualties:Fatalities: 113
Airplane damage: Destroyed
Airplane fate: Written off (damaged beyond repair)
Location:near Vrbovec (   Croatia) show on map
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
Flightnumber: 475
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).
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."


Classification:
Mid air collision
Loss of control

Sources:
» Air Disasters
» Aviation Week & Space Technology
» Collision course / by Tony Brkic

Official accident investigation report
investigating agency: Air Accidents Investigation Branch (AAIB) - United Kingdom
report status: Final
report number: AAIB AAR 5/1977
download report: Report on the collision to British Airways Trident, G-AWZT and Inex Adria DC9, YU-AJR, in the Zagreb area, Yugoslavia, 10 September 1976 (AAIB AAR 5/1977)

investigating agency: Air Accidents Investigation Branch (AAIB) - United Kingdom
report status: Final
report number: AAIB AAR 9/1982
download report: Report on the accident to British Airways Trident, G-AWZT and Inex Adria DC9 YU-AJR, Zagreb Yugoslavia, 10 September 1976 (AAIB AAR 9/1982)
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Map
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).

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HS-121 Trident

  • 11th loss
  • 117 built
  • 2nd worst accident (at the time)
  • 3rd worst accident (currently)
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 Croatia
  • 2nd worst accident (at the time)
  • 3rd worst accident (currently)
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