New Delhi, May 7 (PTI): The number of air-miss incidents in the country have grown in the past two years due to heightened traffic density over major airports.

According to official figures, the number of such incidents have risen from 2.041 per lakh movement of air planes in 2003 to 2.081 in 2004, 2.506 in 2005 and 2.559 last year.

Several measures were being taken to avoid air-miss incidents, with the government making it mandatory for all aircraft to have the Airborne Collision Avoidance System (ACAS) or Traffic Collision Avoidance Systems (TCAS) installed in them, besides expanding the radar coverage to monitor every breach of minimum separation between aircraft.

Official sources said the Airports Authority of India was also installing automatic dependent surveillance and controller pilot data link at Delhi and Mumbai airports to reduce the manual burden of the Air Traffic Controllers.

They said most of the busy airspace and air routes were covered by the mono-pulse secondary surveillance radars (MSSRs), which warned the ATC, enabling them to alert the pilots in a timely manner, they said.

The ATC personnel were also being trained and re-trained on the modern equipment being installed.

However, there was a shortage of ATC personnel required to support the unprecedented growth in aviation, they said, adding the heavy air traffic had necessitated the opening of some additional units at existing airports in Delhi, Mumbai, Chennai, Kolkata and Nagpur. This would require the recruitment of an additional 620 ATC personnel, they said.

The sources said several other measures were also being taken to meet the congestion problem, including restriction of non-scheduled operations in peak hours.