On 3 July 1968, BKS Air Transport Flight C.6845, an

Airspeed Ambassador The Airspeed AS.57 Ambassador is a British twin piston-engined airliner that was designed and produced by the British aircraft manufacturer Airspeed Ltd. It was one of the first postwar airliners to be produced. The Ambassador was developed i ...

registration ''G-AMAD'' of

BKS Air Transport BKS may refer to: * BKS theory, on interaction of matter and electromagnetic radiation * BKS Air Transport, UK airline 1951-1970 *BKS (band), a Canadian techno group created by radio DJ Chris Sheppard, with Hennie Bekker and Greg Kavanagh *BKS, Fa ...

crashed at

Heathrow Airport Heathrow Airport (), called ''London Airport'' until 1966 and now known as London Heathrow , is a major international airport in London, England. It is the largest of the six international airports in the London airport system (the others be ...

, damaging two parked

Trident A trident is a three- pronged spear. It is used for spear fishing and historically as a polearm. The trident is the weapon of Poseidon, or Neptune, the God of the Sea in classical mythology. The trident may occasionally be held by other marine ...

airliners as it cartwheeled into the incomplete

Heathrow Terminal 1 Heathrow Terminal 1 is a disused airport terminal at London Heathrow Airport that was in operation between 1968 and 2015. When it was officially opened by Queen Elizabeth II in April 1969 it was the largest new airport terminal in western Euro ...

, then under construction. Six of the eight people on board the Ambassador were killed, along with the eight racehorses being transported on it. citing ''Aircraft Illustrated'' Vol.1, nr. 4 (Oct. 1968), p.127 The crash was blamed on the failure of a flap-operating rod due to metal fatigue, resulting in asymmetrical lift.

Accident

The Ambassador, construction number 5211, had previously been British European Airways' ''Sir Francis Drake''. It had recently been converted to a "horsebox" transport and was on a flight from Deauville, France, to Heathrow Airport. Flight C.6845 was transporting eight

racehorse Horse racing is an equestrian performance sport, typically involving two or more horses ridden by jockeys (or sometimes driven without riders) over a set distance for competition. It is one of the most ancient of all sports, as its basic pr ...

s belonging to businessman William Hill together with five grooms. As the aircraft was landing on Heathrow's runway 28R the left wing dropped, and the

wing tip A wing tip (or wingtip) is the part of the wing that is most distant from the fuselage of a fixed-wing aircraft. Because the wing tip shape influences the size and drag of the wingtip vortices, tip design has produced a diversity of sha ...

and left

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

touched the grass adjacent to the runway. The crew tried to increase power to

go-around In aviation, a go-around is an aborted landing of an aircraft that is on final approach or has already touched down. A go-around can either be initiated by the pilot flying or requested by air traffic control for various reasons, such as an unstab ...

and climb away, but the

bank angle A banked turn (or banking turn) is a turn or change of direction in which the vehicle banks or inclines, usually towards the inside of the turn. For a road or railroad this is usually due to the roadbed having a transverse down-slope towards the ...

increased. The aircraft hit two parked empty

British European Airways British European Airways (BEA), formally British European Airways Corporation, was a British airline which existed from 1946 until 1974. BEA operated to Europe, North Africa and the Middle East from airports around the United Kingdom. The a ...

Hawker Siddeley Trident The Hawker Siddeley HS-121 Trident (originally the de Havilland DH.121 and briefly the Airco DH.121) is a British airliner produced by Hawker Siddeley. In 1957, de Havilland proposed its DH.121 trijet design to a British European Airways (B ...

s, knocking the tail fin off one (''G-ARPI'') and slicing off the entire tail section of the other (''G-ARPT''). The Ambassador cartwheeled following the impact and slid upside down coming up against the ground floor of the terminal building where there was an explosion. Six people on board the Ambassador died, including the flight crew and three of five

groom A bridegroom (often shortened to groom) is a man who is about to be married or who is newlywed. When marrying, the bridegroom's future spouse (if female) is usually referred to as the bride. A bridegroom is typically attended by a best man an ...

s, along with all eight horses. The other two grooms were seriously injured as were two people on the ground. A further 29 people on the ground received slight injuries. Of the two Trident aircraft, G-ARPT was damaged beyond economic repair and G-ARPI was subsequently repaired. G-ARPI was involved in an accident in 1972 resulting in the deaths of 118 people and becoming the deadliest non-terrorist aviation accident in the UK. A Viscount (G-APKF) received slight damage. The Viscount was also repaired but later too involved in a fatal hull-loss accident in Cambodia as XW-TDN in 1975. All other Ambassadors were grounded pending the result of an inquiry. The starboard rod from the aircraft was tested and found satisfactory but rods from some other Ambassadors showed signs of cracking and when tested failed in a similar manner to G-AMAD's port rod. The rods on aircraft were strengthened and shown to be capable of 37,000 hours flight time.

Probable cause

The port (left)

flap Flap may refer to: Arts, entertainment, and media * ''Flap'' (film), a 1970 American film * Flap, a boss character in the arcade game ''Gaiapolis'' * Flap, a minor character in the film '' Little Nemo: Adventures in Slumberland'' Biology and he ...

operating rod had failed due to

metal fatigue In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...

. While the mechanism had failed, the compensating mechanism between the two sets of flaps remained intact. The port flaps had retracted but the compensator caused the starboard ones to extend further. The resulting asymmetry of lift resulted in the roll to port. The pilot probably tried to overshoot and set the flaps to the correct 10 degrees, but due to the mechanism design this was not sufficient to cause the starboard flaps to retract (which would have taken 25 seconds in any event). The Department of Transport report concluded that whatever the pilot's actions, it was "doubtful" whether an accident could have been avoided. After the accident all Ambassadors were fitted with steel reinforcements to the flap operating rods.

References

External links

Photograph of severed tail section of Trident 1 G-ARPT
– taken in 1972

* ttp://www.airteamimages.com/hawker-siddeley-trident_G-ARPI_bea---british-european-airways_66991.html Photograph showing damage to tail of Trident 1C G-ARPI
Trident accidents and incidents

* a 1969 ''Flight'' article
A short clip showing the accident of G-AMAD
{{DEFAULTSORT:Bks Air Transport Heathrow Crash Aviation accidents and incidents in 1968 Airliner accidents and incidents caused by mechanical failure 1968 BKS Air Transport Heathrow crash 19680703 19680703 BKS Air Transport Heathrow crash 1968 disasters in the United Kingdom July 1968 events in the United Kingdom History of the London Borough of Hillingdon

Accident

Probable cause

See also

References

Further reading

External links