Airports where pilots could fear to land : Valley Vision

On October 25, 2024, there was an incident involving a Qatar Airways Boeing 787 that was operating as a scheduled flight from Colombo, Sri Lanka to Doha, Qatar. After landing and taxiing at slow speed to the assigned bay, the plane’s right main landing gear sank into a ramp area, which in turn collapsed. As the plane’s main landing gear wheels had sunk in deep, the right engine made contact with the ground and sustained damage. It is fortunate that the incident did not happen on the runway or on the taxi track when the plane would have been at a higher speed.

Social media posts indicate that a Japanese company contracted to build the airport at Doha — most of it is on reclaimed land — had suggested that the whole area would need to be concreted as the soil was not strong enough to handle the stress that would be induced by heavy aircraft movement. As the cost was prohibitive, a cheaper option was chosen. It is surprising that a cash-rich country would cut costs on an important infrastructure project that is one of the most important in the fast growing aviation scene.

Singapore’s Changi airport, Hong Kong’s new airport at Chek Lap Kok island, and Male airport (the Maldives) are built on reclaimed land and have been functioning and expanding rapidly. They have not encountered the kind of problem seen at Doha. However, it is certain that Qatar will leave no stone unturned in correcting any deficiency found in the airport operational area constructions.

Chennai airport’s expansion

Why is this incident of interest to India? People may not be aware of the original expansion plan of Chennai airport that had been proposed in 2007. The design project was originally given to the firm, Larsen & Toubro (L&T), with the Airports Authority of India (AAI) involved in the requirements. Under the plan, a parallel runway to the existing main runway was to be constructed, and the old secondary runway was to be extended across the Adyar river (which flows near the airport area), with a bridge to connect the two runways. L&T carried out the soil testing for the bridge to be built across the river, which would hold the taxi track and the area assigned for the parallel runway. It appears that the firm found the soil for the area required for the parallel runway to be unsuitable, and the proposal for a parallel runway was dropped.

The AAI then proposed that the taxi track across the river be converted into the extended secondary runway and that L&T needed to do fresh soil testing for the expanded project. For reasons best known to L&T and the AAI, L&T dropped out of the project. Instead, the project was awarded to an unknown construction company, Consolidated Construction Consortium Limited (CCCL), which, at that stage, had no experience of building even a road bridge. The AAI claimed that the bridge construction design had been approved by IIT Madras. This writer has a letter from the Head of the Department of Structural Engineering, IIT Madras, stating that they had only validated the numbers given by the AAI.

Safety violations, unaddressed issues

In the Environment Clearance No. 10-140/2007-IA-III dt. 25/8/- 1, it was indicated by the AAI that the runway bridge, with a span of 200 metres by 415m and a structural grid of 20 mx10m, on a RCC column of 1.2m diameter and 1.4m high above a high floodline, would be constructed on the Adyar river. The flood level in earlier floods was 13m and so the bottom of the bridge should have been 14.4m above mean sea level. The pillars supporting the bridge across the Adyar were to be 1.2m in diameter, but the pillars constructed are 0.86m in diameter. The area that the bridge was to occupy was 200m x 417m but it was stretched to 617m. The most serious violation was the caveat that the bridge had to be built 1.4m higher than the flood level of the Adyar river in the earlier floods. But the bridge has been built four metres below the permitted level. During the catastrophic floods in Chennai in 2015, the gushing water flow in the Adyar river was blocked by this structure, resulting in an accelerated water flow through the lower portion of the secondary runway. This resulted in the Coast Guard hanger, private aircraft parked on the tarmac and also an Army bridge near the Indian Army’s Officers Training Academy (which is next to the airport) being destroyed.

The floods in 2015 were blamed on the delayed opening of the sluice gates of Chembarambakkam lake (one of Chennai’s water supply sources) which lies 14 kilometres west of the airport. Environmentalists say the water discharge from Chembarambakkam contributes only around 30% of the water flow in the Adyar river, with the rest from overflow from flooded waterbodies further west such as Mudichur, Sriperumbudur and Parandur (the planned site of Chennai’s second airport) We have seen what Chennai and the surroundings went through during the deluges in 2021 and 2023. Weather pundits expect extreme weather events ahead.

This brings us back to Doha and its connection with Chennai airport. The AAI completed the Chennai runway extension more than 12 years ago and the AAI claims that it is designed for Airbus A380 operations. Recently, in a review of operations at Chennai airport, a Cabinet Minister in the Tamil Nadu government said that efforts are on to get Code F aircraft (much larger widebody aircraft such as the A380) to operate to Chennai. He said the AAI is working on this. To operate such aircraft, you need a runway and taxi track width of 60m. This would need even wider spacing from the existing main runway. The runways in Chennai are only 45m wide. If one applies the standards set by the International Civil Aviation Organization, no Code F plane can operate. Can the AAI explain why no widebody aircraft can operate on the secondary runway, even though it was completed 12 years ago?

Near the Parandur airport site
| Photo Credit:
THE HINDU/B. VELANKANNI RAJ

A greenfield project

Now to the much proclaimed greenfield Parandur airport project. The plan here is for the acquisition of 4,000 acres of land for a new international airport which is an area rich in waterbodies. To have such an airport built to international standards, soil testing and concreting of the entire area will have to be done in order to operate large aircraft. Based on the experience of the dropped parallel runway project at the existing Chennai airport, are crores of tax-payers’ money going to be sunk in a project which will destroy the many waterbodies at Parandur? If 4,000 acres of concrete — and for a depth of at least 4m — are to cover waterbodies, can one imagine where flood waters from those destroyed waterbodies would flow? We are in an era of climate change. Let us not forget that constructing an airport on reclaimed land that is situated in an area of waterbodies is a specialised subject, and the costs are prohibitive.

Readers may wonder why this writer has mentioned the depth of a concrete tarmac. Readers might be aware of hard landings of 2g or 3g. In simple terms, ‘g’ is the acceleration due to gravity. So, a 2g landing for an aircraft that weighs 400 tons is equivalent to the weight on its wheels of an impact of 800 tons. Apart from such an impact, if an aircraft lands when there is a strong crosswind, the wheels, rather than being straight, may be at 30°-45° angle to the runway. On touchdown, the aircraft’s wheels straighten as the aircraft moves along the runway. The runway surface, apart from the impact of the aircraft, will also be subject to a twisting force. The Minister has talked about a plan for even larger planes landing at the existing Chennai airport. And Parandur airport is being planned in an area with waterbodies. One can imagine the huge twisting impact that an aircraft weighing 600 tons will have on a runway when landing in a crosswind. There has to be a professional in charge who has good knowledge on how to design a runway and operational area structures, and who also has knowledge of operational issues.

We have read reports of several bridges built in recent times across India collapsing like a pack of cards. Lives have been lost. We must not lose sight of the issue of safety.

Bengaluru has now established itself as the aviation gateway to the south, a position Chennai once held. Tamil Nadu has lost its premium gateway position because of procrastination, bad planning and design. The fact is also that inflated numbers projecting rising air passenger numbers in Tamil Nadu cannot conceal the truth. Passenger numbers have not even touched 40% of their original projections. It seems to be a case of fools rushing in where angels fear to tread.

Captain A. (Mohan) Ranganathan is a former airline instructor pilot and aviation safety adviser. He is also a former member of the Civil Aviation Safety Advisory Council (CASAC), India