For more than 125 hours, the Air Force and Navy have scoured the hills and forests of Arunachal Pradesh. They have been aided by the Army, local police, state government, paramilitary forces and the local population but since the An-32 transport aircraft went missing Monday, search teams are yet to find clues.
The aircraft, with 13 people on board, went missing while flying from Jorhat in Assam to Mechuka in Arunachal Pradesh. And so far, the IAF has employed its helicopters, transport aircraft, UAVs and other sensors, along with navy’s P8I aircraft. All electronic, radar, optical and infrared sensors including satellites have also been used to scan the area for any probable clues.
According to IAF officials involved in the search and rescue mission, the inaccessible hilly terrain of the area which is sparsely populated along with the bad weather prevalent this week has made the search very difficult. They also clarified that the ‘Sabre-8’ emergency locator transmitters (ELT) beacon, which sends a distress signal in the event of a crash, only has battery life of 36 hours and is unlikely to be active now, making the search more challenging.
Also, the total search area for the An-32 is more than a 1000 square kilometres, IAF officials told The Indian Express, based on where the missing aircraft was last in touch with the base and its final destination. This is the area formed by an approximate triangle between Along, Payum and Mechuka in Arunachal Pradesh. Along and Mechuka are around 45 km away from Payum to the South and West respectively.
“The route goes from Jorhat to Along and then to Payum where we take a turn towards Mechuka ALG. The aircraft was last in touch with us just ahead of Along, and so we are searching the whole area after the last known location as per SOP,” said a senior IAF official.
“This is a problem peculiar to the North-East and it can happen to even the most modern aircraft. Depending on how the aircraft met with the accident, it may have disintegrated and parts sprayed all over. The terrain is hilly and densely forested with thick canopies, unlike say Uttarakhand, which makes a visual search from the air next to impossible.”
According to the official, the area is also inaccessible with hardly any villages or population which makes reports from the ground minimal. “Even our own ground troops will take time to reach any of these areas, leave alone conduct a thorough search. I can understand why people would expect something as big as an aircraft to be located quickly but the North-East takes time,” the official said.
Responding to criticism that the outdated ELT beacon was responsible for the delay in locating the aircraft, the official said that “people forget that ELT is a line of sight device, it needs to be directly in line to communicate with the satellites or any helicopter flying above. In case of the area we are looking in, the device could have rolled over and gone into a gorge or in a gap which limits its line of sight except to a helicopter flying exactly above it. ELT device works fantastically well in plains but not in such terrain”.
The official also said that the ELT beacon has battery life of 36 hours. “We had only 3-4 hours available on Monday before nightfall and then bad weather the next day, virtually limiting the time available for searching,” the official said.
The new ELT beacon has an extra feature. Besides sending the same signal, it also sends the exact GPS location which makes it easier to pinpoint and reach the device. “Without any signal, it would have made little difference, contrary to what some people are arguing,” the official said.
Meanwhile, the IAF said in a statement that some family members of those on board the missing aircraft met Defence Minister Rajnath Singh Thursday, where they were briefed about the search efforts. The IAF has also been in touch with separately, it added.
Refusing to speculate on the cause of the An-32 aircraft going missing, an IAF pilot who has flown on that route said that “when an aircraft goes suddenly missing with no radar or radio contact, there are two possibilities. One is CFIT or controlled flight into terrain where the pilot is disoriented in space – he is fully in control but he loses sense of where he is due to clouds and goes into a mountain. This kind of thing is more unlikely in a modern aircraft but this was an old one. Second is a catastrophic incident, say an engine explosion, the chances of which are minimal.”
“CFIT can happen there because of the terrain in which we are flying. The aircraft doesn’t fly very high because it doesn’t want to go above the clouds and lose contact with the ground in the valley areas,” said the pilot.