MUMBAI: A split-second decision taken by an Air India pilot and air traffic controllers to abort a take-off helped avert a horrifying collision at Mumbai airport on Monday morning. 
The heart-stopping high-speed drama unfolded in the span of less than a minute when an Indian Air Force (IAF) helicopter of President Pratibha Patil’s VVIP squadron landed on runway 27 on which an Air India aircraft was speeding towards take-off at the same time. The Air India aircraft aborted its take-off and came to a halt barely 300 metres from the IAF chopper. 
Expectedly, the blame game began even as radio telecommunication recordings between the ATCOs, IAF and AI pilots were confiscated by officials of the Directorate General of Civil Aviation, for investigation. The IAF, which will also be inquiring into the matter, said through its spokesperson that their "pilots had followed the instructions from Bombay Approach (Air Traffic Control) meticulously". Officials of the Intelligence Bureau also reached Mumbai airport later in the day to do a background check of the personnel involved and rule out sabotage.
The incident took place at 9.17am peak-hour traffic time at Mumbai airport, with six civilian aircraft circling in the air for landing and an equal number on the ground, waiting for departure. As per norms, the ATC was informed in advance about the VVIP movement. "At 9.17am, Pratap 1, one of the three MI-17 helicopters of the President’s squadron, reported to the radar controller that it was three miles away from the Mumbai airport. Three IAF helicopters were flying in formation and only the leader of the pack is in touch with the ATC," said a source from air traffic control.
Take-off permission was given at 9.17am to a Mumbai-Delhi flight, IC-866, which had lined up on runway 27. An A-321 generally takes about 30-40 seconds to take off. At Mumbai airport, there is either a landing or a take-off every 90 minutes. "Since a VVIP movement was expected, a three-minute gap before and after the VVIP flight was kept. Pratap 1 was to land at 9.20am; the AI aircraft would have taken off before 9.18am," the source added.
But seconds after the A-321, with 148 passengers and seven crew members on board, commenced its take-off roll with full-on power, the tower controller, who physically keeps a watch on the runway, saw an IAF chopper touching down near the end of runway 27, which is near taxiway Charlie.
"The A-321 had accelerated to a little above 120 knots (222 kmph) when the commander got a ‘Stop Immediately’ instruction thrice from the ATC. Had the stop order been given three seconds later or had the commander not acted quickly, it would have resulted in a crash since the A-321 would by then have crossed 145 knots (262 kmph), which was the decision speed for this flight, in three seconds," said an airline commander.
Decision speed or V1 is the speed at or below which a take-off can be safely aborted. Once an aircraft crosses that speed, the pilot has to continue the take-off procedure under any circumstance. Any attempt to brake or halt the aircraft after decision speed is likely to end in a crash as the plane would speed out of the runway. Then again, if such an incident had taken place on a rainy day, even at 120 knots, the A-321 would have crashed into the IAF helicopter as braking action is poor on a wet surface.
The commander of the A-321, Captain S S Kohli (who is also an instructor pilot), wondered how the chopper could have landed when he (Kohli) had been given clearance by the ATC for take-off. "The chopper just landed without taking a landing clearance. I cannot say much more," Capt Kohli said. The commander steered the aircraft into rapid exit taxiway Whisky, which is located between the runway intersection and the end of runway 27. The IAF helicopter was just 300 metres away from the A-321 when the latter came to a halt.
"There seems to have been no communication between Pratap 1 and Pratap 2. Pratap 1, the only helicopter in touch with the Mumbai ATC, landed at 9.20am and Pratap 2 landed at 9.17am without informing the ATC," said an airport source, adding that as the choppers were flying low they were not detected on the radar.
"It was a dramatic braking action as sparks flew and smoke rose from the aircraft wheels and the fire brigade engines sped to the spot anticipating a fire,” said the source. Said an A-320 commander: “It could have ended in a catastrophe as all the ingredients for a disaster were present. Here was an aircraft trying to stop at high speed with sparks flying off its wheel even as it sped along with full fuel tanks and full passenger loads.”
For the passengers, the seriousness of the situation dawned when the A-321 took the turn into the taxiway and exposed the IAF chopper to full view of its passengers. “There was complete silence inside the cabin. Then the commander informed us about the aborted take-off,” said a cabin crew member on board the flight.
Then at 9.20am, as scheduled, Pratap 1 landed on runway 27, followed by the other IAF chopper at 9.21am. Sources said that Pratap 1, which landed at 9.20am, had Patil, along with Maharashtra governor S C Jamir and some other dignitaries on board. An IAF spokesman said in New Delhi: "The pilots of the chopper had followed the instructions from Bombay approach meticulously. The presidential entourage was cleared to take off from INS Kunjali and land at Santa Cruz between `R’ (Roger) and `W’ (Whiskey) taxiways. An inquiry has been ordered by the IAF into the incident”.
The inquiry may include questioning of officials responsible for sanitizing the airport which is mandatory before and during a VVIP movement. IAF sources said that as per the norm, before every VVIP movement the airspace has to be closed for other flights, clearly indicating lapses on the part of the ground controlling authority. The President was to fly to Gondia, which is also civil aviation minister Praful Patel’s constituency, by her special IAF plane to attend a function.
"The A-321 aircraft taxiied into bay no 18, following which an announcement was made that it would have to wait for 30 minutes for the wheels to cool off. But later, an announcement saying that the wheels would need repairs was made. Passengers were given an option to cancel their journey and about 20 of them alighted. The other passengers were moved to another aircraft which took off by 1pm," said a cabin crew member.
At Mumbai airport, helicopters land on the runway and then taxi to their parking bays. Choppers are not allowed to land directly onto parking bays. "Parking bay 23 was allotted for the IAF helicopter carrying the President and she was to board another aircraft parked in bay 24 Alpha," said a Mumbai International Airport Pvt Ltd (MIAL) spokesperson.
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