Tabletop Runway

Some airports that are located in mountainous regions have tabletop runways. Having no choice, these tabletop airports are certainly dangerous, engineering marvels and, therefore, sometimes cause accidents. 

What went Wrong on August 7?

It was Friday, and a Boeing 737 of Air India Express, on August 7 overshot the runway. It was a repatriation flight from Dubai to Kozhikode and was flying to a special event of Vande Bharat. There were a total of 10 infants, 174 passengers, 2 pilots and 4 cabin crew on board. It is the first major and notable accident only after the 2010 crash at the Mangaluru Airport. The flight fell 35 feet down the slope, and this caused the aircraft to split into two as the runway at Kozhikode has deep gorges surrounding both sides. Though there was no fire on board, both the pilots died on the spot. There were casualties among passengers and injuries of varying degrees. Yet again, the spotlight has turned to such airports and their operation due to the accident.

What Exactly is a Table Airport?

• As per a retired aviation official, there’s no such term (tabletop airport) in the technical documents of the International Civil Aviation Organisation. However, the Directorate General of Civil Aviation (DGCA), the statutory aviation body in India, categorizes these airports in such a manner so that the safety measures are highlighted during operations on the runways. In actuality, there are not many differences between a tabletop airport and a normal airport. 

• The best way to determine the concept of a tabletop airport is to think about the analogy used in the name. It’s similar to any runway that is situated on the top of a table. There is a steep drop at both ends of the runway, and sometimes the measurement reaches hundreds of feet. The runways are similar to those of the flight decks on aircraft carriers. The difference here is, the runway on aircraft carriers is short in the distance when compared to tabletop runways. Despite having longer distances, accidents still occur due to a number of reasons. 

Why are these Runways a Death-Scape for Pilots?

These runways are actually constructed on top of a mountain. By chopping off the uppermost part of the peak and carving the sides, it forms like a plateau. These are certainly impressive examples of engineering where it is possible to construct longer runways even in remote areas and on top of the mountains. The interesting part is, these tabletop airports equipped with such unique runways are suitable not just for regional airlines but also for long-range international airlines. 

As the runway is constructed on elevated terrains, the problem lies in last-minute manoeuvring due to lack of space. This is one of the major reasons for many pilots, as landing and taking off seems to be challenging on these runways. At least twice in a decade, such accidents have occurred with Air India Express planes. It is not necessary that a tabletop airport is bound to be situated on the mountain. 

There are some which are even built on islands. These are also referred to as tabletop airports. Though they have the usual length of runways still, the rate of threat remains the same whether it’s mountain or island. Some airports with a shorter runway (shorter than the usual length) construct the turf on an upward slope so that gravity plays a vital role in assisting the landing of an aircraft. These airports usually don’t accommodate larger aircraft. 

How many such Airports are there in India?

There are a total of 6 tabletop runways in India. These are:

•  Shimla and Kullu (Himachal Pradesh) – 1163 metres

• Pakyong (Sikkim) – 1700 metres

• Mangaluru (Karnataka) – 2449 metres

• Lengpui (Mizoram) – 2500 metres

• Kozhikode and Kannur (Kerala) – 2850 metres

Why are these Runways Almost Dangerous to Pilots?

The only flaw with the tabletop airport is the design of the runway. The runways start, and the end is filled with dangers. There is very tilted room for errors, and therefore, pilots require the best of the best training to land on such runways. As per the pilots, such runways are at constant risk for landing. There is a minimum margin for overshooting. Therefore, the landing requires precision with little to no room for errors. 

Also, they can be hazardous no matter what the weather or time of the day. As the runways are constructed along the lines of the horizon (edge of the mountains), an optical illusion is created that camouflages the drop. Pilots with no such experience of landing can misjudge the remaining length of the runway resulting in overshoot. Therefore, pilots need to be extra careful and ensure that they land on the exact mark (not too late or not too early) so that the speed can be checked before the drop.

The pilots also complain that the buffer zone is very less in such tabletop runways in India when compared to other normal airports in the country. The hazard of undershooting or overshooting can be a common problem in such runways leading to grave situations.

Problems with Accessible Roads:

It is said that tabletop airports have a major problem with the access roads that are constructed around the airfield. These roads play a vital lifeline in the case of an accident. As per the reports, most of the accidents occur during the phases of landing and taking off. Due to the huge momentum of an aircraft, a downward slope can actually worsen the outcome. This was the very same case in terms of the accident that occurred on May 22, 2010, in Mangalore or Mangaluru. It is recommended to level the downward slope to prevent accidents. 

Probable Steps that can be taken by DGCA:

• EMAS can be installed at the tabletop airport in Kerala. It is an Engineered Material Arresting System, a form of arresting bed that is mandatory for all International airports in the United States. This, too, should be prioritised in India.

• This material led system is installed at the end of the runway and helps in holding back the aircraft. This can help a lot in the cases of overrun aircraft. 

• Airports have a range of visual aids to support pilots in bad weather or during low visibility. These systems must be enhanced in order to prevent accidents.

• Indian Civil Aviation Safety Board should be made independent for focusing on the safety issues related to every flight and suggest proactive measures accordingly. 

• Tabletop airports can be dangerous for heavy lifting aircraft as their momentum requires longer runways or at least the required space for survival. Smaller and narrow-body aircraft have no issue with landings on tabletop runways.