Ananth Krishnan

Only DGCA probe will unravel mystery of Mumbai mix-up

MUMBAI: Seconds after clearing Air India flight IC 866 for takeoff on a busy Monday morning, air traffic controllers at the Mumbai airport had a nasty surprise. At the southern end of Runway 27, just as the Airbus-321 was gathering speed to take off, an air traffic controller spotted an Mi-17 helicopter, part of the President’s convoy, making its descent, reportedly three minutes ahead of schedule. The controller quickly alerted Air India Captain S.S. Kohli. It took two frantic commands from Air Traffic Control (ATC) in the space of 10 seconds for the pilot to slam on the Airbus-321’s emergency brakes and avert a major disaster seconds before it was too late.

A day after the events unfolded, there remains some mystery over what actually caused the mix-up. Airport sources said the IAF helicopters carrying President Patil and her convoy had not received landing clearance from the ATC control tower, and arrived early. The sources said the first helicopter that landed did so without any clearance from the tower, and the second that followed only alerted the tower when it was already above the runway. An IAF spokesman strongly denied these claims, maintaining that the convoy “followed ATC instructions meticulously.”

According to sources who have accessed ATC transcripts, the Mumbai ATC cleared flight IC 866 for takeoff at 9.17 a.m. and the three helicopters of the Presidential convoy were allotted an Estimated Time of Arrival at 9.20 a.m. The sources said the helicopter Pratap 2, the first of the convoy to land, touched down at 9.17 a.m. The Mumbai airport, India’s busiest, handles up to 32 takeoffs and landings every hour in peak times — that is about one aircraft movement every two minutes.

Here, three minutes can make a world of difference.

Airport sources said the convoy had not received clearance to land from the ATC Tower, which is responsible for controlling aircraft movements and issuing clearances. Only the leader of the convoy, Pratap 1 — believed to be carrying Ms. Patil — was in communication with the Approach Radar, as is common practice. Once the leader receives clearance for landing, the clearance applies to the whole convoy. The Approach Radar, which maintains contact with aircraft up until they make their final approach, issued a command to Pratap 1 “clearing for their final approach” and asked the convoy “to contact the control tower” for further instructions.

Here is when, the sources said, things began to go wrong. Before Pratap 1 could make its approach, the second chopper in the convoy, Pratap 2, reportedly landed on Runway 27 without any clearance. Pratap 1 soon followed, communicating with ATC only when already above the runway.

Normal procedure requires landing aircraft to contact the Control Tower when making their final approach, usually 4 miles from the runway. Sources indicated that two helicopters in the convoy, Pratap 2 and Pratap 3, were possibly experiencing technical difficulties communicating with the leader of the convoy, Pratap 1, which may have caused some confusion.

By the time the Approach Radar warned the ATC tower of the convoy’s arrival, issuing a command “transferring Pratap formation” to the tower’s control, the two helicopters were already on the runway.

A stunned ATC Control Tower replied: “Pratap formation already landed. Asked IC to reject takeoff.”

Air safety expert Capt. A. Ranganathan, who has worked on the DGCA’s Approach and Landing Accident Reduction (ALAR) project, said it was unlikely that the helicopters would have received clearance from the Control Tower. “If indeed the IAF helicopters were in touch with the Control Tower, then the pilot of IC 866 would have certainly heard the communications between the tower and the helicopter as he was also on the same frequency,” he said. “The fact that he did not hear it means the helicopter was not on tower frequency. The convoy should have contacted the Control Tower for clearance.”

Until the DGCA’s probe announces its findings, the debate is set to continue.

More In: Today's Paper