There is no reason to ring alarm bells but the increasing congestion in air traffic — almost a 29 per cent jump in traffic last year alone — has also been accompanied by an increase in the number of “air misses.” While it is only the odd air miss, involving a VVIP flight, that gets publicised, the Directorate General of Civil Aviation (DGCA) has replied to a Right to Information request filed by The Sunday Express that on an average, there were two such incidents each month last year involving virtually all carriers, public and private — and Indian Air Force aircraft.The standard definition of an air miss is when two planes flying below 29,000 feet breach the mandatory 1000-feet separation limit. Above 29,000 feet, the limit is also 1000 feet for aircraft that have Reduced Vertical Separation Minima (RVSM) equipment which include Transport Collision Avoidance System (TCAS), special altimeters and transponders. Those not RVSM-complaint have to maintain a separation of 2000 feet. Incidentally, all passenger aircraft are now RVSM-compliant. The Indian Air Force is working to upgrade its VVIP fleet Boeings to RVSM.Detailed data on air misses for five years — from 2002 to 2006 — show that there have been 83 reports of such air encounters and that over 15 such incidents have already occurred in 2007. Between 2002 and 2005, there were only two air misses involving IAF aircraft — with Turkmenistan Airlines and Indian Airlines in 2003 — but in 2006 alone, the IAF was involved in six such episodes. While one of these six was an air miss involving two IAF AN-32s, the other incidents involved aircraft of Jet Airways and Indigo Airlines.Technically, DGCA doesn’t distinguish between “air misses” and the more serious “air proximity” incidents where pilots, after having breached the separation limit, are also on “converging tracks and in eyeball-to-eyeball contact.” Officials said the “ratio” of air misses to traffic volume compares well with that of several other countries but the increasing trend is a matter of concern.
