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Small yet smart enough to handle flights in fog, rain

delhi Updated: Jul 28, 2009 00:23 IST
Sidhartha Roy
Sidhartha Roy
Hindustan Times
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The Indira Gandhi International Airport is going to be better equipped to deal with air traffic congestion this winter.

The Runway 27/09 of the airport, the smallest of the three runways at IGIA, would now have CAT I Instrument Landing System (ILS), which helps pilots to land their aircraft even in poor visibility conditions.

The runway has CAT I ILS on the 27 end (towards NH 8) of the runway, but there was no instrument landing system on the 09 side, which is towards Dwarka.

Usually, the two bigger runways of IGIA — runway 28/10 (3.8 km) and runway 29/11 (4.4 km) — are used for flight movements.

Runway 27 is used as a backup runway when one of these is closed for maintenance or technical problems.

When fog hits the airport every winter, bad visibility slows down flight movement and leads to congestion. With CAT I ILS at only one end (27), the smaller runway is usually kept closed during fog.

Instrument landing system is a ground-based instrument approach system that provides precise guidance to an aircraft approaching a runway.

It uses a combination of radio signals and high intensity lighting to guide the aircraft when the pilot can't actually see the runway due to fog or rain.

The aircraft needs an ILS receiver to follow the signals.

“We would install a CAT I ILS on the 09 end of the secondary runway. With this all the three runways at the airport would be equipped with ILS,” said an Airports Authority of India (AAI) spokesman.

The airport is managed by private operator Delhi International Airport Ltd. (DIAL), but air traffic services are still managed by the government-owned AAI.

The 2.8 km-long Runway 27 is now closed for recarpeting and installation of CAT I ILS, which would take a few months.
“The runway would be ready for operation before winter. In fact, we want to start recarpeting of Runway 28 after this if we have enough time,” said a DIAL spokesman.

Using CAT I ILS (CAT refers to category) an aircraft can land even when the runway visual range (RVR - the runway as visible from an airborne aircraft) is as low as 550 metres.

The airport’s runway 29, commissioned last year, has CAT IIIB ILS on both ends, which helps aircraft to land in visibility as low as 50 metres.

Apart from a new instrument landing system, runway 27 would also get more RVR measuring machines. There is only one at the runway at present.