When two aeroplanes collided mid-air near New Delhi, because... killing...

The Ahmedabad Plane Crash involving 195 passengers and crew members on board has raised many questions and recalled many incidents. People still remember how a Boeing 747 and an Ilyushin Il-76 cargo plane collided mid-air on November 12, 1996. The incident took place at Charkhi Dadri, around 100 kilometres from the national capital New Delhi when the Boeing 747 en route to Dhahran and Kazakhstan Airlines Flight 1907 en route from Chimkent, Kazakhstan collided in the air. It was the deadliest aviation accident ever in India and the world's deadliest mid-air collision that killed 349 people. 

It was found after investigation that the Kazakh crew failed to maintain the correct altitude and collided with the Saudi Arabia flight. The poor English language skills in the Kazakh cockpit and the inadequate interpretation of directions provided by air traffic control caused the crash.

Crew Members

Saudia Flight 763, a Boeing 747-168B, with 312 people on board took off from Delhi for Delhi–Dhahran–Jeddah route. The crew on consisted of Captain Khalid al-Shubaily, First Officer Nazir Khan, and Flight Engineer Ahmed Edrees. Al-Shubaily was a veteran pilot with 9,837 flying hours. On the other hand, Kazakhstan Airlines Flight 1907, an Ilyushin Il-76TD was on a charter service from Chimkent Airport to Delhi. The crew consisted of Captain Alexander Robertovich Cherepanov, First Officer Ermek Kozhahmetovich Dzhangirov, Flight Engineer Alexander Alexanderovich Chuprov, Navigator Zhahanbek Duisenovich Aripbaev, and Radio Operator Egor Alekseevich Repp.

What happened?

The Lahoti Commission, headed by then-Delhi High Court judge Ramesh Chandra Lahoti probed the mid-air collision. The commission said in its report that the accident occurred due to the fault of the Kazakhstani Il-76 crew. The plane descended from the assigned altitude of 15,000 to 14,500 feet and subsequently came down to 14,000 feet. There was a serious breach in operating procedure, the Kazakhstan aircraft pilots could not properly understand what was said to them in English. The Kazakh crew relied entirely on Radio Operator Repp for communications with the ATC. First Officer Dzhangirov and possibly Captain Cherepanov misunderstood Dutta's final radio call and assumed that the Saudi 747's altitude (14,000 feet) was their own assigned altitude.

Miscalculation, Lack of English language

Indian air controllers also told the Lahoti Commission that the Kazakhstani pilots sometimes confused their calculations, they were accustomed to metre altitudes and kilometre distances, while most other countries use feet and nautical miles for aerial navigation.

However, Repp realised that the pilots were flying below the required 15,000 feet and brought it to their attention. Cherepanov ordered to fly the plane at full throttle, and the plane climbed, only to hit the oncoming Saudi Arabian plane. The tail of the Kazakhstani plane broke and the left wing of the Saudi Arabian jet was hit, tearing away both parts from their respective planes.