Officials inspect the wreckage of an Air India Express jet at Calicut International Airport in Karipur, Kerala, on August 8, 2020.
Officials inspect the wreckage of an Air India Express jet at Calicut International Airport in Karipur, Kerala, on August 8, 2020.
Photo: AFP

On Friday night a rather horrific plane crash left 18 people dead and many others injured. The Air India flight had overshot the runway while trying to land at Kozhikode International Airport and broken into two pieces.

Reportedly, the pilot had aborted two landing attempts due to tailwind and had circled the airport several times before the final ill-fated landing. According to Arvind Singh, the Chairman of the Airport Authority of India, the plane could not land at the intended runway. "Then landing was tried on another runway where the mishap happened," he said.

Later in the day, the Calicut Airport took to Twitter stating that they were now operational again. However, the dangers associated with the runway itself remains a concern. Kozhikode International Airport has the state's only tabletop runway. Across India, there are only five such runways, and many experts agree that they pose challenge to pilots and does not leave much room for error.

What is a tabletop runway?

Built on hilly or uneven terrain, a tabletop runway resembles a plateau of sorts. They are built by levelling a hill and so, there are steep drops on one of both sides.

Why are they dangerous?

Essentially, a tabletop runway requires extreme precision while landing a flight. If there is a cliff at the end of the runway, the pilot is required to stop the plane at the correct distance, lest it fall. With heavy rains however, the massive vehicle can slip. Additionally, such runways can often create an optical illusion that it appears to be nearer than it actually is.

Civil aviation safety expert, Captain Mohan Ranganathan had been quoted by NDTV as saying that the runway Calicut has a steep downslope and no safety area. When one combines this with tailwind and the slick conditions created by rainwater, it becomes even more dangerous.

In 2011, Ranganathan had warned that flights landing on runway 10 in tailwind conditions in rain at the Kozhikode airport endangered the lives of people onboard those flights. With tailwind conditions, the descent of an aircraft at the time of landing might be affected.

Are there other tabletop airports that have similar issues?

There are four other airports with tabletop runways that are under the Airport Authority of India. The others are at Mangalore in Karnataka, Pakyong in Sikkim and Shimla and Kullu in Himachal Pradesh. Lengpui Airport in Mizoram also has a tabletop runway and is operated by the state government.

In May 2010, another Dubai Air India Express flight, travelling to Mangalore had overshot the runway and fallen into a gorge. The plane had exploded after catching fire, killing more than 160 people. Eight passengers had survived the horrific crash. Here too, it had been a tabletop runway that was being used.

Apart from this, the two year old Pakyong airport close to Gangtok is notable. Spread over 201 acres, this is something of an architectural marvel. At a height of 4646 ft, it is one of the five highest airports in India.

The airport has a 1.75 km runway with a width of 30 metre. It has a 116-metre-long taxiway connecting it to an apron measuring 106 metre by 76 metre that can simultaneously accommodate two ATR-72 aircraft.

But the airport faces problems due to low visibility owing to poor weather conditions, being originally planned and designed as a Visual flight rule (VFR) Airport. At present there are no commercial passenger flights travelling to the airport. Technical aspects have also been hampering flight operations. The issues include a lack of Instrumental Landing System, radar and adequate runway area. Currently, the runway is only two-kilometres long and 80 metre wide as against the minimum mandated 150 metre. Presently, aircraft land and take off as per visual flight rules.

(with inputs from agencies)

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