Wednesday, July 27, 2016

Strategy planned to use Sagarnidhi technology to hunt for missing aircraft

C Shivakumar
Chennai:
As the search and rescue operations on the surface of the sea to locate the debris of missing Indian Air Force (IAF) transport Aircraft AN 32 carrying 29 passengers failed to yield results, the focus on the fifth day was how to carry out the search to the depth of 3,500 metres to locate the aircraft.

Marred by rough seas and no exact location of where the aircraft went down, the search is being conducted by extrapolation to the time of the crash and the only hope is to catch the signals emanating from the flight decoder recorder which is feared to be under the sea at a depth of 3,500 metres. And sources are hoping this could be achieved by National Institute of Technology research vessel ‘Sagarnidhi’ as it has the most advanced sonar, multi-beam echo sounder.

While the sonar of Indian submarine can’t come handy at such a depth, it is learnt that research vessel Sagarnidhi’s multi beam echo sounder can travel upto 6,000 metres depth. Like other sonar systems, multibeam systems emit sound waves in a fan shape beneath a ship's hull. The amount of time it takes for the sound waves to bounce off the seabed and return to a receiver is used to determine water depth.

Besides that, the ship also has sub-bottom profiler that scans the seabed for anything protruding above it. Indian National Centre for Ocean Information Sciences (INCOIS) director Satheesh C Shenoi, who holds the additional charge of NIOT director, said that it is the only option left with the team conducting search and rescue operation.

Shenoi said that the technology was used during the hunt for Coast Guard’s missing Dornier but then the given area had no Dornier in it. “It was found in the area where the Reliance vessel was conducting the searches,” Shenoi clarified.

The issue with the search operation is that the depth of the sea where the aircraft went missing has not been mapped unlike being done in Economic Exclusive Zone. Interestingly, across the world less than five per cent of oceans have been mapped. Shenoi says that mapping of the oceans is a costly exercise and it could be done unless there is a purpose.

Shenoi says that it won’t be a easy task for Sagarnidhi and the resolution which it will get while conducting the search operation won’t be that clear.

However, Shenoi feels that AN-32 has an advantage over MH-370, the Malaysian aircraft, which went missing on March 8, 2014. they don’t know the time when it went down and the search area was 800 to 900 square nautical miles. “In this case we know at what time the aircraft went down, as such we have the location,” he says. But with the search being conducted on extrapolation to time the aircraft went down and the rough seas which took away the radar image, the search and rescue operation could only hope for a a success.

Why Sagarnidhi?
1.It is the only research vessel in India which has a specialised sonar called multi-echo sounder and sub-bottom profiler
2.This can go upto the depth of 5,500 metres and profile the ocean bed for the missing aircraft.
3.The Indian Navy has a vessel which can profile a depth till 1,000 metre.
4.Since the sonar beacon is not working the only hope is to get signals from the flight decoder
5.The underwater search when compared to the missing Malaysian aircraft MH370 hunt has an advantage as there is a given time and the area has been demarcated

Challenges for search and rescue ops:
1.The ELT of the aircraft is not functioning
2.The sea is rough as such waves took away the radar images
3.The search is being done by extrapolating the data to the time when aircraft went down

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