After remaining unmanned for over 48 hours, some vital installations at Calcutta airport developed technical snags.

A radar and the middle marker on the primary runway of the airport that had suffered problems were restored with great difficulty, airport sources said. Although there were some delays in flights, no major disruption occurred.

The runway radar, called Instrument Landing System, and the Doppler Very High Frequency Omni Range and Distance Measuring Equipment, used to guide aircraft to the airport, have not been attended to since nearly 3,000 employees of the airport stopped work from February 1.

They are protesting the Centre?s decision to award the contract for modernisation of Delhi and Mumbai airports to private parties.

The gadgets are operated by air traffic control (ATC) personnel, but are maintained by the communication-technical wing of the airport. However, officers of the wing are on relay hunger strike, and with drivers of vehicles also on ceasework, regular maintenance is not possible.

Both the channels of the Monopulse Surveillance Secondary Radar (MSSR) tripped in the morning. The radar was repaired only after Indian Air Force (IAF) personnel, who have taken over the airport?s fire service, took technical wing officers to the MSSR. The radar helps the ATC maintain surveillance of the aircraft till 250 nautical miles.

?It took about an hour to restore it and flights were slightly delayed due to this,? an officer said.

On Thursday afternoon, the middle line marker of the runway, a gadget that transmits beams to the aircraft and helps it land, also developed a snag. It was repaired after IAF personnel took their technical staff to the runway.

?All the installations require maintenance every 24 hours. This has not been done for the past three days,? an officer said.

Nonetheless, flight operations from Calcutta were near-normal. But fewer passengers chose to fly, airlines sources said.

Littered all over, and without any air-conditioning and lights and an inoperative conveyor belt, the airport could not have been in a worse condition.