Chennai/New Delhi:Debris from an Indian Air Force An-32 aircraft (bearing tail number K-2743), which had gone missing over the Bay of Bengal on July 22, 2016 during an operational mission to Port Blair, have been located in the seabed 310 km off Chennai coast by an Autonomous Underwater Vehicle (AUV) of the National Institute of Ocean Technology, officials said on Friday.
How scientists stumbled upon debris?Scientists at the Chennai-based NIOT stumbled upon its debris when they were testing the instruments of their newly-acquired AUV for seabed mapping in December.
It was during such a testing expedition undertaken by Research Vessel Sagar Nidhi on December 9-10 last year, about 310 km off the Chennai coast, the instruments on the AUV picked up some strong SONAR reflections from the seabed at a depth of 3,400 m.
High signal strength-The strong signals intrigued the scientists who then decided to dive deeper for a closer look.
"Then we dived a little deeper and took some photographs, which were shared with the Indian Air Force through the Ministry of Earth Sciences," G A Ramadass, Director, NIOT told PTI.
Ramadass said the IAF confirmed that the debris was of the AN32 aircraft that had gone missing more than seven years ago.
Tricolour roundel found-Another scientist said initially the debris was thought to be of a shipwreck, but on closer examination the researchers were able to identify the tricolour roundel found on IAF aircraft.
What has NIOT done so far?The NIOT had joined the search operations in July 2016 along with other agencies and used surface ships and remotely operated vehicles for the purpose. "At that time we did not find anything," Ramadass said, adding that the scientists stumbled upon the debris while calibrating instruments of the AUV.
According to the Ministry of Defence, the NIOT, which is part of the Ministry of Earth Sciences, had recently deployed the AUV with deep sea exploration capability at the last known location of the missing An-32.
"This search was conducted at a depth of 3,400 m using multiple payloads, including a multi-beam SONAR (Sound Navigation and Ranging), synthetic aperture SONAR and high resolution photography. Analysis of search images had indicated the presence of debris of a crashed aircraft on the sea bed approximately 140 nautical miles (approx. 310 Km) from the Chennai coast," the statement added.
The capabilities of AUV-The AUV, procured from Norway in 2022, can dive up to a depth of 6,000 metres to map the seabed and was on an expedition to look for gas hydrates in the Bay of Bengal.
N R Ramesh, a senior scientist at NIOT, said the AUV can be pre-programmed for carrying out underwater surveys and its entire journey can be monitored from the research vessel.
A single mission of the AUV takes about 26-28 hours from lowering into the sea to its retrieval after the survey.
The scrutiny-The search images were scrutinised and found to be conforming with an An-32 aircraft. This discovery at the probable crash site, with no other recorded history of any other missing aircraft report in the same area, points to the debris as possibly belonging to the crashed IAF An-32 (K-2743).
What happened?The ill-fated An-32 aircraft belonging to 33 Squadron of IAF which is located at Sulur, Coimbatore, was on a scheduled courier sortie from Tambaram IAF Base (Chennai) to Port Blair, when it went missing. The aircraft took off from Tambaram at 8.30 am with 6 crew members and 23 passengers. It was scheduled to arrive at Port Blair at 11.45 am.
After the aircraft did not make any contact with Air Traffic Control of Port Blair, the IAF initiated an overdue action. According to the IAF, the last known radar location recorded by Chennai Air Traffic Radar was East of Chennai at 151 NM and the aircraft was flying at 23,000 ft.
The travellers-Of the 29 onboard, six were crew members. There were 23 passengers: 11 from the IAF, two Indian Army personnel, an Indian Coast Guard personnel, one sailor from the Indian Navy and eight civilians working with the Navy.
Massive Search and Rescue(SAR)-The IAF deployed two of its C-130 aircraft equipped with Electro-optical and Infra-Red sensors while the Indian Navy pressed its P8i aircraft equipped with Synthetic Aperture Radar along with Dorniers in the SAR operation. The Navy also deployed its 13 ships in the search area and was assisted by six ships of the Indian Coast Guard. One of the Indian Navy's submarines was also used to locate the missing plane.
The Maritime Rescue and Coordination Center at Chennai coordinated the round the clock surveillance towards search effort along with Southern Air Command of IAF, Indian Navy and Indian Coast Guard, until the SAR was called off on September 15 that year.
The IAF wrote to the families of 29 members who were aboard the ill-fated plane, apologising to them that it had failed to locate the missing aircraft and was left with no option but to declare those onboard "presumed dead".
According to the IAF, more than 200 sorties were carried out, scouring an area of 2,17,800 square nautical miles while ships from the Navy and Coast Guard searched nearly 28,000 square nautical miles of sea. The eastern coast was searched for any possible debris washing ashore, which never did.
Closure to families-Sources in the defence and military establishment said efforts will now be focused on bringing closure to the families of people who were on board the aircraft. They said all possible ways will be explored to retrieve the wreckage and take remedial measures so that such an incident does not recur.
"We want to bring closure to the families," said a source.
The Antonov-32 is a Soviet-origin turboprop twin-engined military transport aircraft. (with PTI inputs)
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