An unexplained descent to disaster by Kazak aircraft

“What flight level has been ordered for us?” he asked Egor, who was sitting in a niche in the cockpit below. Egor took four seconds to respond. “Keep the 150-th (15,000 feet), not descending,” He had realised the incoming “traffic” was flying at almost an identical height. Would they hit?

Four more seconds passed before Captain Cherepanov cried out to his crew: “Regim!, Sanya!” The Captains words resounded in the cockpit. Five seconds more lapsed before Egor bellowed his final warning: “get to 150 (15,000 feet), because on the 140th (14,000 feet), that one, uhhhhh…”

It was 6.41 pm. All life ebbed from the 37 people on board the IL-76 as it collided with the Boeing 747, with 314 passengers on it. For four long seconds the microphones in the cockpit recorded the deafening sounds of the crash. The blips on New Delhi’s radars disappeared as the two planes, now aflame, plunged into the cotton fields of Charkhi Dadri, 40 kilometres from New Delhi.

Five months after the disaster, all the documentary evidence pointing to the cause of the crash — one of the worst in aviation history — have been submitted to the court of inquiry, headed by Justice R C Lahoti. The evidence includes bulky transcripts of the Digital Flight Data Recorders (DFDRs) and the Cockpit Voice Recorders (CVRs) of the ill-fated planes as well as the report of the accident inspector, K P S Nair.

It was at the request of lawyers appearing on behalf of the two airlines that the DFDRs and CVRs, called the “black boxes” in common parlance, were sent abroad for decoding. While the equipment of the Boeing was decoded at the Air Accident Investigation Board (AAIB), Farnbrough, UK, the decoding of the Kazak equipment was done at the Interstate Aviation Commission (IAC), Moscow.

The IAC transcripts were the last to come in, and it is the English translation of the IL-76’s CVR which has proved to be most revealing.

The transcripts reveal, for the first time, that it was the Kazak pilots who had climbed down from their assigned height and this single fact has now changed the scope of the Lahoti inquiry from how the crash took place to how the IL-76 descended to the height at which the Boeing was flying.

As far as the ATC is concerned, the transcripts show that the Kazak’s pilots were informed about the approaching Boeing 747 just 68 seconds prior to the crash and about the height at which it was flying, 38 seconds before. While the Kazak pilots were informed late, the pilots of the Boeing 747 were never informed about the approaching IL-76.

Most important are the disclosures about the altitude at which the collision occurred. The altitude question was expected to generate a great deal of controversy, but representatives of the Kazak Airlines too have admitted that the IL-76 had climbed down from its assigned height of 15,000 feet to 14,000 feet. An affidavit submitted to the court on April 25, states that 51 seconds before the crash, the IL-76 was cruising at 15,000 feet. By the time the ATC informed them about the altitude of the Boeing, the plane had climbed down to 14,496 feet. And just 26 seconds before disaster, they had dropped to 14,190 feet.

The question is: why? According to representatives of Kazakhstan Airlines, the steep fall in altitude was caused by the “severe turbulence” encountered by the plane 32 seconds before the crash. Due to the turbulence, the pilots had trouble in gaining height and had also switched of the autopilot of the plane.

The lawyers of the Saudia Airlines have contested this version. In a statement submitted on April 30, they have argued that it was impossible for an aircraft to climb down about 970 feet as a result of turbulence without there being even a whimper among the crew members about the adverse weather conditions. The technical data indicates that the Kazak crew tried to lift the aircraft only a few seconds before the collision, by which time disaster was staring them in the face.

Thus, the conclusion of the experts arguing the case for Saudia Airlines is that the descent of the IL-76 was not due to turbulence but that it was a “conscious” act.

They have also submitted that there were a plethora of “contributory” factors which ultimately led to the crash. There appeared to be “utter confusion” in the cockpit in the moments preceeding the crash. This was coupled with secondary factors like the language problem and trouble with converting figures from feet to meters and from kilometers to miles. Yet another factor could be what has been described as “defective” configuration of the cockpit” and cockpit “mis-management.”

Both sides have highlighted the negligence of the ATC and have directed the courts attention to secondary factors like the non-installation of the Vertical Seperation Radar in New Delhi airport.

The Kazakstan Airlines has stated that this and the fact that the approach to and from the international airport at Delhi is through a single corridor is a reason for causing the mishap.