Split-second decision expected of pilots as airport tries new system

MUMBAI: A new landing-takeoff procedure will be launched at Mumbai airport on May 5. The Directorate General of Civil Aviation has instructed it to be followed on a trial basis for three months, said an ATC official.

If successful in Mumbai, the procedure, which entails landings and takeoffs in quicker succession, may be replicated in other congested airports like Delhi and Bangalore. While Mumbai may be the first airport to carry out the trial in India, airports like London's Heathrow and New York's JFK, and the one in Newark have been following the practice for more than a decade. In the UK, it is called 'land-after procedure'. In Mumbai, it is being called 'landing clearance based on anticipated separation'.

The idea is to pack in more landings and takeoffs per hour, especially during the morning peak hours of 9-11.30am and evening peak hours of 5-8pm. That in turn would mean less time spent circling in the sky waiting to land, eventually resulting in a reduction in the quantum of delay.

In Mumbai, the 12,000-feet main runway, called 09-27, handles a major chunk of flight operations. The new procedure will be practiced only during day time and initially only on the main runway. Also, in the initial weeks, the procedure will be undertaken only for a few hours; as confidence builds, it will be spread out throughout the day, the ATC official said. The procedure would be a bit demanding for pilots, especially those who fly only on domestic routes, as it will involve a shift in perception.

To land an aircraft on a runway, a pilot has to get mandatory "landing clearance" from ATC. Currently, that comes in the form of three words: 'Cleared to land'. Before this instruction is given to the pilot of a descending aircraft, the controller ensures that what lies ahead in front of the aircraft is a clear, unobstructed runway, waiting for the aircraft to touch down.

"Under the new procedure, though, when the landing instruction is given, the runway will be anything but clear of aircraft," said a senior commander who has done such landings at Heathrow. For, even as an aircraft is rolling for takeoff, the controller would have given landing clearance to a descending aircraft. Or, there may be aircraft waiting in sequence to land and the second or third aircraft would have already received landing clearance. In short, it is left for the landing pilot to ensure that the aircraft that is taking off has lifted and has cleared the runway before the landing aircraft crosses the runway's threshold to touch down. If that is not the case, the landing pilot has to do a go-around.

In the end, the procedure is one of many that congested airports the world over are forced to follow. As aircraft in the sky increase, they need to be bunched tighter.

Currently, about 11 km of horizontal separation is maintained between landing and takeoff aircraft. With the new procedure, the separation will be reduced to 9.5-10km. A horizontal separation of 7.5km is maintained between two arriving aircraft, which would be reduced to about 5.5km.

Source:  http://timesofindia.indiatimes.com