Three new radars at the airport will make air traffic movement over the city and its surrounding areas safer within a couple of years.

“There will be a new primary surveillance radar, while two secondary radars will also be installed,” S.P.S. Bakshi, regional executive director (east), Airports Authority of India (AAI), said on Monday.

AAI officials in Delhi said Rs 30 crore has been sanctioned for the project, which will include construction of buildings to house the radars and instal equipment.

The primary surveillance radar, also known as approach surveillance radar (ASR), helps locate the position of an aircraft, while the mono-pulse secondary surveillance radar (MSSR) records its speed and altitude.

The ASR radiates electromagnetic waves that bounce off the aircraft and relay back to the radar, giving the plane’s location. The process does not require the Air Traffic Control to establish contact with the pilot.

With flights to and from the airport and those overflying the city increasing rapidly — there has been an over 30 per cent growth in the past three years — the upgrade in the surveillance system was necessary. The existing primary radar is more than nine years old and often develops snags.

“The ASR will be installed inside the airport but the two new MSSRs will be placed outside,” said Bakshi. A survey will be conducted to identify the site. The two radars will have to be set up around 300 km to the north or northwest of the airport. “They will have a greater range than the existing ones and ensure better route navigation,” said Bakshi.

According to airport officials, the existing primary radar needs regular maintenance and sometimes has to be shut down. On June 5, the radar had to be shut down for 45 minutes in the afternoon for repairs.

“Regular preventive maintenance work is required for any radar but when it becomes old, it needs major maintenance frequently,” said a senior official of Calcutta airport.

The ASR and MSSR have a common antenna and if one has to be shut down for maintenance, the other automatically stops functioning. Communication officials then have to ensure proper distance between aircraft. This delays flight operations.

Airports Authority Officers’ Association (India), eastern region, had written to AAI Delhi stating the difficulties and asking for replacement of the key surveillance equipment. “It was a long-standing demand and we are happy that we will get new radars,” said Samir Banerjee, regional secretary of the association.