September 21, 2008

Get Set for More Delays at IGI

By Neha Lalchandani

NEW DELHI: After experiencing several delays, the new runway at Delhi's IGI airport is now likely to be opened on September 25. However, this is only going to lead to another long series of delays, this time affecting the reduction in the distance maintained between two aircraft which has become necessary for effective handling of congestion over Delhi.

According to sources, officials would require about a month's time to assess the working of the new runway and see how much time an aircraft would take to vacate the airstrip before the new separation minima can be implemented. However, with winter round the corner, it will not be possible to implement the new procedures during the fog period.

At present, the separation minima is about 5 nautical miles which is set to be reduced to about 3 nautical miles. This will go a long way in reducing congestion by allowing more landings per hour. Delhi handles around 35-40 flight movements every hour which comes to around 680 per day. With the new runway in use and the reduced distance between aircraft, flight movements could go up to even 70 per hour. Mumbai, on the other hand, handles about 720 flights per day.

"Once the new runway is operational, the airport will follow exclusive use of runways and we will require at least a month to assess how much time an aircraft will take to vacate the runway. On the basis of that, we will be able to judge what minimum distance needs to be maintained between two approaching aircraft. Only then, the new procedure will be notified," said senior officials.

Along with this, the performance based navigational system, the procedure that defines the height to be maintained by an aircraft at a particular distance from the runway and in relation to other aircraft, will also be delayed. Though the procedure exists on paper at present, it would soon be available to the pilot in his cockpit through a computer programme. This will reduce the interface between pilots and the air traffic control, making the flying system more systematic and smooth.

An AAI official added that according to International Civil Aviation Organisation rules, a minimum distance of 2.5 nautical miles between aircraft was essential, but several countries followed the rule of 3 nautical miles. In India, due to lack of infrastructural facilities, a distance of 5-7 nautical miles has been the norm.

Sources said that normally, there are three crucial factors determining the horizontal distance - the time taken by a pilot to vacate the runway, the speed and size of two aircraft operating one behind the other and any other unforeseen hazard. "By reducing the distance the reaction time available to both the ATC and the pilot comes down. There have to be enough measures in place to ensure that safety is not compromised," said an official.

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