1996 Charkhi Dadri mid-air collision
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Saudi Arabian Airlines Flight 763 (SV 763), registration HZ-AIH, was a Boeing 747-168B en route from New Delhi, India, to Dhahran, Saudi Arabia, on November 12, 1996. Air Kazakhstan Flight 1907 (9Y 1907), registration UN-76435, was a Ilyushin IL-76 en route from Shymkent, Kazakhstan to New Delhi. The two aircraft collided in mid-air over the village of Charkhi Dadri, Haryana, India, killing all 349 on board both aircraft. It is the deadliest mid-air collision in aviation history.
History and cause
Flight SV 763 departed Delhi at 6:32 PM local time. Flight 9Y 1907 was at the same time descending to land at Delhi. Flight 9Y 1907 was cleared to descend to 15,000 feet when it was 74 miles from the airport while Flight SV 763, traveling on the same airway as Flight 9Y 1907 but in the opposite direction, was cleared to climb to 14,000 feet. About eight minutes later, around 6:40 PM, Flight 9Y 1907 reported having reached 15,000 feet. At this time the controller advised the flight, "Identified traffic 12 o'clock, reciprocal Saudia Boeing 747, 14 miles. Report in sight."
When the controller called Flight 9Y 1907 again he received no reply. He again warned of Flight SV 763's distance, but no reply came. Flight 9Y 1907 had crashed into Flight SV 763 almost head-on. The left wing of Flight 9Y 1907 sliced through the aft and tail sections of Flight SV 763. While Flight SV 763 disintegrated almost immediately, the fuselage of Flight 9Y 1907 remained structurally intact until ground impact. Despite rescue attempts for at least 3 inital survivors, all 312 persons on board Flight SV 763 and all 37 persons aboard Flight 9Y 1907 perished. Both aircraft plummeted to the ground and crashed on a field.
Crash investigation and report
The crash was investigated by the Lahoti Commission, headed by then-Delhi High Court judge Ramesh Chandra Lahoti. Depositions were taken from the air traffic controllers Guild, and the two airlines. The flight data recorders were decoded by the respective airlines under supervision of air crash investigators in Moscow and London.
The commission determined that the accident had been the fault of the Kazakh IL-76 commander, who (according to FDR evidence) had descended from the assigned altitude of 15,000 feet to 14,500 feet and subsequently 14,000 feet and even below that. The report ascribed the cause of this serious breach in operating procedure to the lack of English language skills on the part of the Kazakh aircraft pilots; they were relying entirely on their radio operator for communications with the ATC.[1] Kazakh officials stated that the aircraft had descended while their pilots were fighting turbulence inside a bank of cumulus clouds. The counsel for the ATC Guild denied the presence of turbulence, quoting meteorological reports, but did state that the collision occurred inside a cloud.[1] This was substantiated by the affidavit of the crew of a US military aircraft flying in the vicinity who witnessed the crash. [2] The ultimate cause was held to be the failure of the Kazakh pilot to follow ATC instructions, whether due to cloud turbulence or due to communication problems.
The air-crash investigation report also recommended changes to air-traffic procedures and infrastructure in New Delhi's air-space: Separation of in-bound and out-bound aircraft through the creation of 'air corridors', installation of a secondary air-traffic control radar for aircraft altitude data, mandatory collision avoidance equipment on commercial aircraft operating in Indian airspace and reduction of the airspace over New Delhi which was formerly under exclusive control of the Indian Air Force.
The Civil Aviation Authorities in India made it mandatory for all aircraft flying in and out of India to be equipped with an ACAS (Airborne Collision Avoidance System). This was the first time in the world that ACAS was mandatory.
Disaster in popular media
This disaster was shown in the documentary "Head On!" on the National Geographic Channel. And it will also show in Canadian Television series, Air Crash Investigation.
See also
References
- ^ a b Communication gap caused Charkhi Dadri mishap, Rediff; retrieved July 4, 2006
- ^ Charkhi Dadri collision occurred in "heavy clouds": US pilot, Rediff; retrieved July 4, 2006
External links
- Saudia Flight 763 report from the Aviation Safety Network
- Air Kazakhstan Flight 1907 report from the Aviation Safety Network
- 10th anniversary article on the collision - Flight Safety Australia, Nov-Dec 2006 issue - PDF 268 KB
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