Flight services were disrupted at Kempegowda International Airport (KIA) for the third consecutive day on Thursday due to fog and bad weather.
As many as 32 flights, 19 departures and 13 arrivals were delayed due to poor runway visibility between 6.40 am and 8.30 am on Thursday, airport sources told Deccan Herald. Over a dozen flights on Tuesday and around 35 on Wednesday were delayed due to fog.
At KIA, fog is normally anticipated from November 15 to February 15, between 3 am and 8.30 am. The fog most likely to occur at KIA is known as radiation fog which forms on clear, still nights when ground loses heat by radiation, and cools. The ground in turn cools the nearby air to saturation point, resulting in fog formation.
In fact, December 2 to February 15 is considered as ‘bad weather period’ for flight departures and arrivals at airports across the country. But, unlike other major airports in the country, KIA has a CAT-I Instrument Landing System (ILS) that is said to be “not efficient” in bad weather when the runway visibility range (RVR) drops. Some major airports have upgraded to CAT-II and even CAT-III ILS to over come the fog problem.
KIA, sources said, has the precision approach runway CAT-I intended for visibility of 550 metres. The Meteorological Department has installed a ‘transmissometer’ in the airfield at both the eastern and western ends of the runway for determining the exact visibility in the direction of approach in terms of RVR.
As the runway at the airport has an east-west orientation, the ILS is available for both approaches. The RVR data is determined automatically using the transmissometer at both ends of the runway for both the approaches.
The runway is also equipped with visual aids in addition to electronic aids. The selection of visual aids, the sources said, depends primarily on the visibility conditions under which it conducts operations and on the type of aircraft operated at the airport.
The ILS at KIA had been designed, installed, tested and commissioned by the Airports Authority of India, which is the Air Navigation Service Providers for all the airports in the country, sources added.