Dense fog at Indira Gandhi International Airport here can occur from December 22 to February 10 and there is a possibility of experiencing 100-120 hours of dense fog during the 2010-2011 season, airport meteorological department director Dr. R.K. Jenamani said on Thursday.

Speaking during a workshop on fog preparedness at the airport organised by the Delhi International Airport Limited, Dr. Jenamani said: “For the time being we are witnessing unusually fine weather and the dense fog season is not expected to be as severe as 2009-2010.”

According to presentations made at the workshop, the IGI Airport is one of the worst dense fog-affected areas in the region as well as in the world. This is because dense fog or CAT-IIIB conditions can remain uninterrupted for eight to 15 hour spells for weeks. The airport suffers more from fog compared to the city owing to its vast airfield. Fog can cause serious decline in both the general visibility and the runway visual range while closure of air traffic occurs if the RVR reduces below 50 metres.

Owing to fog, 217 flights were diverted at the IGI Airport in January this year while a large number of flights were cancelled or delayed. The Delhi airport experiences on an average 47 days of fog in December and January of which dense fog occurs for 16 days. CAT III dense fog conditions usually occur between 11 p.m. and 10 a.m. However, sometimes it can occur at even 8 p.m. and continue well into the next day severely affecting fog operations at the airport.

The airport met department has recommended that for reducing chances of flights diversions, operators of non CAT-III flights should consider the latest fog forecasts, current visibility and trend forecasts before deciding on the time of departure of such flights to the Delhi airport from various other airports in India.

In order to cope with disruptions of flights caused by fog, a number of facilities have been provided at the airport. When visibility falls below 1200 metres, safeguarding procedures are implemented while low visibility procedures are implemented if RVR on a runway falls to less than 800 metres. The airport met office operates a real time round the clock fog monitoring, forecasting and dissemination system.

Planning and slot management vice-president Yudhishter Aggarwal said: “There are improvements in the airport's facilities to deal with fog compared to last year. During the fog season, pilots are assisted in landing by “secure routes with unidirectional flow provided at Terminal-3”. There are also computerised ground lighting panels and 120 CAT III parking stands. Further during low visibility, flights can take off if the visibility is 150/125 metres.”

The terminals too are equipped with a host of facilities and conveniences for passengers who are affected by fog. A round the clock call centre will give fog related information while flight statuses can also be accessed on the airport website.

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