Mar 15, 2014, 09.18PM IST [ Subhro Niyogi ]
KOLKATA: Air traffic controllers at Kolkata have ruled out the possibility of the missing Malaysia Airlines flight MH370 flying over Indian airspace, one of the two possibilities that Malaysian
Prime Minister Najib Razak had suggested at a press conference in Kuala Lumpur on Saturday.
The other alternative route that the flight whose communication system is now believed to have been deliberately disabled is that it flew to the Indian Ocean to the south of the Malacca Strait
where the plane was last sighted on a Malaysian military radar.
Speaking to TOI, air traffic controllers' guild secretary Sugata Pramanik said that while flight MH370 could have avoided detection on the Secondary Surveillance Radar, the blip by the huge Boeing
777-200 ER aircraft would surely have been spotted by the Air Force that uses Primary Surveillance Radars to detect such intrusions. Any flight that moves in the north-western direction towards
Kazakhstan from Malaysia, as suggested by Razak, is bound to pass through Kolkata Flight Information Region. (FIR).
"If an aircraft wants to avoid being seen, they can easily become invisible to a civilian radar by switching off the transponder that relays information about the plane. But it cannot avoid defence
systems. The Indian Air Force has radars in multiple installations across the country and it is inconceivable that none of them spotted the odd blip with no flight clearance," he said.
There are nine Air Defence Identification zones in the country that are manned 24x7 to prevent an enemy aircraft from violating Indian airspace.
Guild member Sushil Mondal concurred, explaining that all hell would break loose if Air Force detected an aircraft that did not have air defence clearance. Any plane flying through Indian airspace
is first required to submit the flight plan and manifest to the air traffic controls in its flight path. This is then relayed to the Air Force for permission.
"There are times when the Air Force finds a blip that does not match a flight plan. That usually happens when flight plans going missing at their end due to a system or link failure. They then
immediately contact us for information. If the plane flight plan isn't of suspicious nature, a clearance is granted. Or else, it is asked to return to wherever it came from. In case, we too don't
have any information of the aircraft, all hell will break loose and the Air Force may even scramble jets to take the plane down. Nothing of the kind happened last Saturday," said Mondal.
Kolkata airport has an Automatic Dependence Surveillance Radar and Controller-Pilot Datalink Communication that enables it to not only trail planes when it is in the radar zone of 60 nautical miles
or nearly 120 km and beyond through very high frequency radio but also through the data link when the plane goes out of voice communication range. There are large areas in the Kolkata FIR,
particularly over Bay of Bengal, that have no radar coverage at present. A radar has been installed in Andaman and Nicobar Islands but is yet to be commissioned.
Not that it would have helped though. According to the Malaysian PM, those in control of MH370 had deliberately switched off all communication devices to fly undetected for nearly seven hours after
it was last sighted on radar.
Incidentally, Kolkata airport too has a primary surveillance radar but it filters out all flights beyond 25,000 ft because it is used for landings and takeoffs. "If we record all the information up
to 46,000 ft, there will be confusion in the ATC. Area controllers look after flights beyond 25,000 ft," explained Pramanik.