An IndiGo flight had followed a similar approach and landing onto the Calicut runway on Friday evening — less than 2 h before the Air India Express flight from Dubai landed and crashed. The difference, however, was that the IndiGo flight was operated with an ATR, a turboprop aircraft, which operates at much slower speeds than the jet-engined Boeing 737.
ATR aircraft typically carry out an approach to land at 110-115 kt (knot = 1.852 km/h), as against Boeing 737, which has an approach speed of about 140-150 kt. Slower the speed of the aircraft, shorter the runway length it needs to cover to come to a halt.
But the IndiGo aircraft had followed a similar flight profile, said Capt Amit Singh, an air safety expert. He relied on data from flightradar24, a live flight-tracking website, which showed that the pilots too had initially lined up to land on the westerly runway 28, like the AI pilots, as this was the runway with headwinds that are favourable for landing. But the IndiGo pilots discontinued the approach to land, which could have been for similar reasons, poor visibility due to rains and cloud cover.
“The IndiGo pilots then made a second attempt and landed on the easterly runway 10, same as the Air India Express pilots,” said Capt Singh. “The IndiGo ATR may have faced less severe weather and the slower turboprop aircraft may have been more forgiving. Nevertheless, this pattern can provide some interesting insights into the prevailing conditions and the interactions between the pilots and the air traffic controller,” he added.
What AIE did that IndiGo hadn’t
Eighteen people including two pilots were killed and scores injured when an AIE flight from Dubai with 190 onboard overshot the tabletop runway in Kozhikode airport on Friday night while landing in heavy rains and fell into a valley 35 feet below and broke into two portions.
The 2,700 m runway at the airport is known as a “table-top”, an aviation term for runways with steep drops at one or both ends. They leave little room for error should a pilot overshoot the runway, either through human error or mechanical failure.
An air traffic control official familiar with the crash confirmed this version of events. He added it was unusual to attempt a landing at the airport with a tailwind, which is typically used for takeoffs.
“The length of the runway in Calicut is around 2,700 m and the plane touched the ground after crossing 1,000 m of the length, leaving less room to bring the aircraft to a halt,” the official, who declined to be named as he is not authorised to speak to the media, said.
“It was windy and rainy and the runway surface was wet. In such instances the weather is dynamic. An aircraft typically lands and departs in a headwind as a tailwind increases the speed of the plane,” the official said.