At IGI,plans afoot to turn down sound on Runway 29

The airport’s lifeline and main runway 28-10 will be shut for repairs from April 8 to September 20 — the court reprieve comes in the wake of the decision. The Runway 29-11 had been closed at night after the locals had complained about the noise.

The Directorate General of Civil Aviation (DGCA) has formed a working group,comprising members from DIAL,Airports Authority of India (AAI),airlines,the Air Traffic Control (ATC) and its own officials,to finalise noise reduction measures.

“The DIAL’s environment department monitors environmental parameters in and around the airport,including noise,and follows a balanced approach for noise control as per the International Civil Aviation Organisation (ICAO),” said a DIAL official. The ICAO approach includes measures like controlling noise at source (by working on aircraft design and engine design for noise reduction),land use management and operating procedures like sticking to flight path,aircraft power (thrust) setting and a continuous descent approach (CDA).

“The DIAL will also be requesting town planning agencies like DDA and MCD to regulate development of residential areas in the runway’s funnel zone,” said a DIAL spokesperson.

The DIAL and DGCA also plans to shift from step landing to a continuous descent approach by flights landing at the airport.

The continuous descent approach requires an aircraft to have a standard power setting from the time it begins descent. The currently used step landing procedure involves frequent changing of power settings.

Pilots say it is difficult to implement CDA in a busy airport like Delhi.

“In CDA,the aircraft makes an even,continuous descent to the runway,” said a senior pilot with the national carrier. “The result is an average noise reduction of four to six decibels. But this will not be practically possible at a busy airport like Delhi.”

In the present landing approach,he said,a pilot needs to inform the ATC at several points of descent: above 15,000 feet; at 10,000 feet; at 5,000 feet. He is granted clearance to land at 2,500 feet.

In CDA,the pilot has to be granted clearance when the aircraft is at 15,000 feet and needs to inform the ATC when he is at 2,500 feet,he said. This needs a lot of advance planning on part of the ground control. The DGCA is now interacting with stakeholders like airlines,the ATC,the Delhi government and the DIAL for a joint action on the issue.

The DIAL has also procured the latest equipment from Germany for measuring noise levels in the runway’s approach path at six locations — known as Aircraft Noise Monitoring Terminals — and a mobile station. These terminals feed a central server connected with the flight information system,which will allow the authorities to identify the noise level of each aircraft.

“The data will help DGCA take specific noise abatement procedures like identification of exact noise source,usage of runways and implementation of CDA for landing and other procedures,” the spokesperson said. Pilots landing on Runway 29 between 8 pm and 10 pm have also been advised to avoid using thrust reversers,which will reduce the noise.

After three PILs — filed by residents of Vasant Kunj,Bijwasan village and a private hospital — alleged severe noise pollution on Runway 29,the DGCA had submitted an affidavit saying Runway 29 would not be used from 10 pm to 6 am. On Wednesday,the Delhi High Court gave temporary relief to the airport authorities.