Eighteen people, including the pilot and co-pilot, were killed when the aircraft, trying to land in torrential rain on Friday night, overshot the tabletop runway at Kozhikode and plunged about 35 feet into a valley.
The investigating team retrieved the black box and cockpit voice recorder after cutting into the floorboard of the cockpit. These devices, considered the most important evidence in determining the reasons leading to an air crash, were sent to Delhi for decoding and analysis.
Officials of the AAIB, Directorate General of Civil Aviation (DGCA) and the flight safety department of Air India Express from Delhi reached the crash site on Saturday morning. A DGCA team from Chennai, too, arrived in Kozhikode. The investigators, who visited the ATC and held meetings with different agencies at the airport, refused to comment on the accident.
A senior official associated with the probe said it was too early to say whether the accident was the result of a technical fault or human error. “All crashes are caused by multiple contributory factors and here preliminary info shows wrong landing due to bad weather as a reason. The about 8,000-foot-long runway of the airport is sufficient for a Boeing 737 to land but it is learnt that the aircraft landed 3,000 feet off. What exactly happened will be clear only after checking the flight history and ATC-pilot communications,” the official said.
Aviation experts visualised various scenarios about what may have led to the accident, ranging from hydroplaning (total loss of friction between the wheels and runway surface due to the formation of a layer of water on the ground) to “optical illusions” created by tabletop runways that can distort the flight profile.
Experts also pointed out that the last-minute change in choice of runway and subsequent wind direction was the pilot’s decision or ATC’s suggestion. There were unconfirmed reports of trouble with the landing gear of the aircraft, but, if that was the case, this was not communicated to the ATC. “The inquiry report should find out all aspects, like weather, wind factor, poor visibility, miscommunication with ATC if any, etc.,” said Bharat Bhushan, former DGCA chief.
Civil aviation minister Hardeep Singh Puri, who visited the crash site on Saturday morning, told reporters, “Let’s not speculate on the cause(s), contributing factors of the crash, and wait for the result of the investigation. We were fortunate that unlike the tragic accident at Mangaluru airport 10 years ago, where the aircraft caught fire, here preventive action minimised the loss of lives.”
The report of the two-year-long investigation into the Mangaluru air crash in 2010, which killed 158 people when an AIE Boeing 737 careened off the tabletop runway, had suggested various measures, including an arrester bed, for tabletop runways. An “Engineered Materials Arresting System”, or EMAS, can reduce the severity of a “runway excursion”, but the Kozhikode airport still doesn’t have such a system.
A DGCA inspection of the Kozhikode runway in 2019 had revealed concerns like “excessive rubber deposits” and had found cracks and stagnating water on parts of the runway.
Watch Kerala air crash: What actually happened at the Kozhikode airport