Mystery plane flies past

An unidentified aircraft blipped on Calcutta airport’s primary radar early on Thursday and didn’t respond to repeated queries from air traffic control (ATC) as it moved southwest before disappearing without a trace.
The ATC team was in a tizzy after the aircraft, spotted 37 nautical miles east of the airport around 3.30am, appeared not to have any transponder to link with the secondary radar that measures altitude and speed. When there was no response from the pilot either, the officials sounded a red alert.
“We tracked the aircraft till 4am but couldn’t find out what type of plane it was and to whom it belonged. We didn’t even know whether it had the standard equipment for voice communication with the ATC. So we contacted the Indian Air Force’s liaison unit,” a senior airport official said.
The mystery deepened when the IAF said that the unidentified plane was “unlikely” to be a defence aircraft on a secret mission or drill.
“We are working on the information (provided by the ATC) and trying to find out what it was,” the chief public relations officer of defence (east), Group Capt. R.K. Das, told Metro on Friday. “It couldn’t have been an IAF aircraft at that hour.”
Under normal circumstances, the secondary radar tells the ATC at what altitude and speed an aircraft is flying. But the aircraft must be equipped with a transponder for the secondary radar to be able to do this.
An ATC official said all scheduled and non-scheduled (private) aircraft pilots flying through Calcutta or any other city’s airspace were required to inform the ATC about their flight plans before takeoff. Calcutta airport had no prior information about an aircraft passing through at that time on Thursday.
Sources said if things had gone wrong the unidentified plane could have been involved in a mid-air collision with overflying commercial aircraft.
21/03/09 Sanjay Mandal/The Telegraph

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Categories: Airports Mar 2009, Safety Mar 2009