A pilot’s-eye view of the main runway at Calcutta airport

Calcutta airport’s worn-out main runway would have to make do with another round of patchwork as the plan to resurface the pockmarked tarmac has been postponed.

In its present state, the runway is a bumpy ride for aircraft with years of patchwork leaving the surface uneven.

Of the 3,627-metre stretch, only 600 metres on either side of the main runway — the touchdown zones where planes land — have had repairs. The work was completed on March 31 but pilots and passengers continue to complain about bumpy take-offs and landings.

The main runway was scheduled to be resurfaced this summer after a study by the Central Road Research Institute last year revealed damage to various portions of the tarmac. The report recommended giving the runway a new surface and laying a sheet of synthetic fabric under the bituminous layers to prevent rainwater from percolating down.

The overhaul was to start by the end of 2013 and be completed before the start of monsoon, but sources said the Rs 60-crore project was yet to be cleared by the Airports Authority of India in Delhi.

The green signal, when it comes, would require the authorities to coordinate with airports abroad before imposing restrictions on emergency landing and take-off for the duration of the project. Calcutta airport handles higher number of overflying aircraft compared to other Indian cities.

“There will also be flight delays for months because the main runway will be closed,” an official said.

The main runway can handle about 30 flights an hour, 10 more than the secondary runway over the same period, sources said.

The last time the main runway had an overhaul was in 2003-04. Resurfacing has been due since 2011 but patchwork is all that the AAI has done to keep the runway in business.

For the latest round of stop-gap repairs, machines were used to peel off four to eight inches of the runway surface and put a fresh coat of bitumen on the two touchdown zones at the northern and southern ends.

“Preventive maintenance has been done at both ends of the main runway as that was urgently needed. The runway requires complete rehabilitation and not resurfacing. Rehabilitation will start after the monsoon as that would require the runway to be closed for a long period. We need to make preparations for that,” airport director B. P. Sharma told Metro.

He said it would take six months to complete the overhaul.

Pilots and airlines have complained repeatedly about the uneven runway that makes for rough landings. “Post repairs, the condition of the main runway has improved but there is still a long way to go. What the runway requires is complete resurfacing rather than patchwork,” said Captain Sarvesh Gupta, senior pilot and chairman of the airline operators’ committee.

The committee has been requesting the AAI over the past few months to resurface the runway.

Most domestic airlines, including IndiGo, Jet Airways and SpiceJet, operate narrow-bodied Boeing 737 and Airbus 319 and 320 aircraft that weigh 60 to 65 tonnes and land at speeds of around 250kmph. Most international airlines operate wide-bodied aircraft — mainly the Airbus 330 and Boeing 777 — that weigh around 350 tonnes each with landing speeds of around 250kmph.

The two runways handle around 250 flights every day, far fewer than Delhi’s average of 900 but with a surface several times more vulnerable to damage.

Apart from normal wear and tear, the runway suffers additional damage due to a rise in the groundwater level till one metre below the runway during monsoon. Accumulated water eats into the bituminous layers, causing the surface to become brittle. Parts of the runway become uneven because of rubber deposits from aircraft tyres.

The runway also suffers from the ravages of extreme weather during different seasons — hot and humid summer days, heavy rain during monsoon and low winter temperature.

Airport director Sharma said the drainage system inside and outside the airport was being improved. Outside the airport, the Calcutta Metropolitan Development Authority and irrigation department are working on a Rs 60-crore drainage project. The AAI is spending another Rs 28 crore on drainage within the boundary walls.

Have you had a rough take-off or a bumpy landing at Calcutta airport? Tell ttmetro@abpmail.com