Chennai: Naval and Coast Guard ships continued to search for the missing Indian Air Force AN-32 aircraft with 29 people on board in the Bay of Bengal on Saturday, with no sightings of any debris so far.
"The search is going on. If there is any substantial development it will be made known," Wing Commander Anupam Banerjee, Public Relations Officer for IAF, told IANS news agency.
But what is it that led to the aircraft go off radar in a matter of seconds without any distress call?
An experienced pilot with the Indian defence forces told IANS that such a development could only be due to a catastrophic accident in a "no talk/radio zone" or "dead zone".
The upgraded AN-32 aircraft belonging to 33 Squadron had taken off from the Tambaram Air Force Station in Chennai at 8.30 am and was on way to Port Blair in the Andaman and Nicobar Islands where it was supposed to land at 11.30 am.
The last blip on the radar was seen at 9.12 am when the aircraft, around 300 km off Chennai, carried out a left turn with rapid loss of height from 23,000 feet, according to the recorded transcript of Chennai air traffic radar.
It was roughly around 15-20 minutes after the take-off that the last contact with the aircraft was established, as per sources.
According to IAF, the AN-32 is a twin engine turboprop, medium tactical transport aircraft of Russian origin. It can carry a maximum load of around 6.7 tonne or a 39 paratroopers. Also, its maximum cruise speed is 530 kmph.
"Planes are designed to fly even during an emergency. There will be reaction time to the pilots facing an emergency to send out messages for help or turn towards safety," an Indian defence forces pilot told IANS.
According to the pilot, an AN-32 aircraft will not drop down like a stone or vanish into thin air in the case of normal emergency, as there will be reaction time.
"But in the case of a catastrophic threat, the pilots will not have the necessary reaction time," he said.
An aircraft will not always be on the radar, he noted.
"If the distance to be travelled is around 1,500 km for instance and travel path involves flying over sea then there are chances that the aircraft could not be in the radar from the city of departure after say around 300 km. And it would come into the radar on the other side only when it is around 300 km from its destination," he said.
"So effectively sometimes there will be a dead zone of 700 km. In smaller aircraft, the pilots switch on to the high frequency for being in touch," the pilot added.
Commenting on the probable cause of the aircraft vanishing suddenly, he said: "The possibilities of different catastrophic events happening in the sky cannot be ruled out."
"For example if an aircraft is caught in a strong thunderstorm, then a plane is as good as a paper caught in the storm.
"The storm will throw the plane like a stone," he said.
According to him, there have been instances when an airplane that was flying at around 35,000 feet altitude dropped down to 5,000 feet but regained control after that.
The other catastrophic events that can happen to a plane were sudden failure of all the engines; devastating fire; fuel leakage, jamming of flight controls, loss of flight controls due to fire; power and electrical failure and others.
He said in the best case scenario if the AN-32 had come down gradually then it would have been picked up by some radar or the pilots would have the time to react.
Normally a plane is fuelled taking into account the emergency deviations that may arise - the need to go back to the airport from where it took off or to some other nearby airport in case of an emergency, he added.
(With IANS inputs)
