The Telegraph
Since 1st March, 1999
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Wanted, radar to fight fog

Regular morning mist has started the countdown to fog fright, but the airport authorities are still not equipped to prevent flight delay because of low visibility this winter.

A radar that could cut down fog delay in Calcutta was sanctioned months ago by the Airports Authority of India (AAI), but it will not be installed this winter. The tender to select a company to set up a surface movement radar (SMR), which guides aircraft on the runway, has been floated but the bidders have not been shortlisted.

The radar makes movement of aircraft on the ground efficient and safe by relaying their real-time picture to the Air Traffic Control (ATC). Delhi airport has the facility.

Absence of the SMR negates the gains of Category (CAT) II Instrumental Landing System, recently installed at Calcutta airport.

The system enables an aircraft to land even if the visibility is 350 metres. The plane cannot, however, be guided from the runway to the parking bay without the radar.

Thus, the runway cannot be used by any other aircraft. When visibility is low, the SMR is also needed to guide planes from the parking bay to the runway for take-off.

At Calcutta airport, visibility often drops below 350 metres, making it impossible for flights to take off, even by using CAT II facilities.

A greater cause for concern is that there is no SMR to guide aircraft on the runway when visibility is between 350 metres and 550 metres and CAT II can be used for take-off, said an airport official.

The Met office has already sounded a warning of dense fog at the end of the month. “There is morning mist almost daily now but it does not affect visibility. In three weeks’ time, however, the city is likely to be covered in dense fog,” said an official at the Alipore Met office. The situation may not improve till the end of January.

If the visibility is low and an SMR is not available, special jeeps with fog lights —known as follow-me jeeps — are used to guide aircraft. The jeep is provided on request from the pilot.

Using a follow-me jeep is time-consuming. “After a flight lands, the follow-me jeep is sent to the holding point, which is just outside the runway. The vehicle guides the aircraft back to the parking bay. The opposite happens during take-off. Once the SMR is installed, the ground movement of flights will be smoother and faster,” said an ATC official.

Another airport official ruled out the possibility of the SMR being put to use this season. “We have already started the process of acquiring the radar. A global tender has been floated. Several companies have carried out basic surveys and submitted bids,” he said.

According to sources, the bidders include companies from Australia, Holland, Norway and the US.

Apart from delays, safety of aircraft during ground movement is the major concern for ATC officials. “When the weather is clear, we can see an aircraft but that is not possible on a foggy day. The problem has been heightened by an increase in the number of flights,” said an official.

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