The new year has not been a happy flying experience for passengers in North India. On the night of January 5, fog over the Delhi airport was so thick that one of the runways was not available for operations between 9 pm on Sunday and 4 am the following day. This affected operations with flights getting cancelled and diverted.

Invariably passengers and those waiting to receive them at airports around the country were agitated as a journey, say between Delhi and Chennai that should have taken less than 3 hours was extended by several hours. Over 130 domestic and international flights recorded delays ranging between 30 minutes and three hours, and some had to be diverted to Jaipur, Ahmedabad and Lucknow.

To find a way out of this yearly mess, a 10-member committee headed by Lalit Gupta, Joint Director General, Directorate General of Civil Aviation, was set up. The Committee, which also has representation from the Indian Meteorological office, airlines and airports, is to look at ways to make Delhi a zero diversion airport, without compromising on the safety of aircraft. The committee has been asked to submit its report by the end of March this year.

But one thing that the Committee will find hard to overcome is that there’s no escaping the annual weather phenomenon that seems to work with clock-work precision ‘whitening-out’ north-west, central and east India in turns each time fog occurs. Flights as well as ground transport are thrown out of gear on an average for 15 days from mid-December as dense to very dense fog descends on the cities, reducing visibility drastically.

Fog gateway The north-west border, extending from Gujarat through Rajasthan to Jammu and Kashmir, provides the gateway for the winter fog to spread into India.

Practically nothing can be done about it; the only way out is resorting to technology (instrument landing system or ILS) that allows precision landing for aircraft.

ILS is a ground-based system that uses a combination of radio signals and high-intensity lighting arrays to provide precision guidance to an approaching aircraft.

The ‘localiser’ component in ILS provides lateral guidance, while the glide slope or glide path system provides vertical guidance to receivers in the aircraft.

CAT-III COMPLIANT At New Delhi, the main (28/10) and third (29/11) runways are equipped with CAT-III B, the latest category of ILS, landing capability. No other airport in the country has this capability.

This means that an aircraft can land even when the runway is not visible from an altitude of 15 metres (50 ft), Jacob K. Philip, an aviation analyst based in Kochi, said.

Horizontally, the aircraft can operate even if objects beyond 45 metres (150 ft) ahead are not visible, he added.

The domestic industry has also been doing its bit to try and cope with fog conditions. DGCA sources indicate that the scheduled airlines had trained 2,248 pilots — 1,283 pilots in command and 965 co-pilots — in ILS carrying out operations in CAT II and CAT III conditions at the end of November 2013.

With fog being a dynamic situation, which can change quickly, pilots with various domestic airlines warn that it is better to be safe than sorry when it comes to operations of flights. So, while the best technology and trained manpower to operate flights might be available in the country the final decision on whether a flight should take off in foggy conditions should be left in the hands of experts.

vinson.kurian@thehindu.co.in

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