Chennai (Tamil Nadu): Aimed at finding minerals in the Bay of Bengal, a recent mission by the Chennai-based National Institute of Ocean Technology (NIOT) ended up solving a tragic maritime mystery, thus bringing to closure the sorrow many families endured all these years.
In barely 30 hours, the NIOT mission managed to achieve something that dozens of deep sea divers, aerial teams, and other search and rescue missions had attempted for several weeks after the disappearance but could not. The wreckage of the IAF An-32, which had gone missing seven years back, was finally found by NIOT's OME (Ocean Mineral Explorer) 6000, an Autonomous Underwater Vehicle (AUV), earlier this month. The discovery signifies the technological edge India has in maritime exploration and rescue missions.
What happened in 2016?
On July 22, 2016, the ill-fated Antonov An-32, which had 29 people on board, mysteriously disappeared in the Bay of Bengal. An-32 is a turboprop twin-engine military transport and is oriented towards flying in adverse weather conditions.
The aircraft on an 'op mission' had taken off from the Tambaram Air Force Station in Chennai at around 8.30 am on the fateful day. It was scheduled to arrive at Port Blair in the Andaman and Nicobar Islands at 11:45 am.
However, the IAF officials lost contact with the aircraft at around 9.15 am, when it was approximately 280 kilometres away from Chennai. The 29 people on board included six crew members, 11 Indian Air Force personnel, two soldiers, and eight personnel attached to the Naval Armament Depot. As the news of the aircraft's disappearance spread, the families of the victims hoped against hope that their loved ones would have survived the tragedy.
What followed was a massive search operation stretched over the next six weeks involving several ships, submarines, and aircraft to unravel what had happened to the An-32. On September 16, 2016, officials called off the search and rescue mission after they failed to locate the debris of the aircraft. The 29 people on board were presumed dead and their families were notified.
Seven years later, the NIOT's AUV found the wreckage of the An-32 aircraft located 310 km off the Chennai coast. The defence ministry said scrutiny of the images captured by the AUV revealed they were of the ill-fated plane.
How OME 6000 found the wreckage
ETV Bharat spoke to the scientists who were part of the deep sea exploration dive and was allowed to see visuals of the OME-6000, the Autonomous Underwater Vehicle that located the An32 debris. Imported from Norway, OME-6000 operates autonomously using the data which is fed before every dive. Visuals of the debris were picked up in the last of the 30-hour dive.
The AUV is 6.6 meters long and 0.875 metres wide and weighs about 2 tonnes. It has an endurance of 48 hours in a single "dive and return to station", which turned out to be the key factor in locating the plane's debris. According to Dr NR Ramesh, Scientist, NIOT, the premier institute has a mandate to develop technologies for the exploration and exploitation of living and non-living resources.
"As a part of developing technology for the exploration of minerals available under the ocean, the NIOT has developed an Autonomous Underwater Vehicle, which is capable of going up to 6,000 metres in depth," Ramesh added. The AUV was on its regular task in the Bay of Bengal when it stumbled upon some "man-made objects" in rectangular size.
"The UAV captured a strong reflection of some objects at 3,400 metres depth in the Bay of Bengal. Upon analysing the images of the sonar, we came to know they are metallic objects which could be the parts of the aircraft lost in 2016," Dr Ramesh said.
The NIOT decided to explore further. "We went close to the seabed to capture photographs of the objects," the NIOT scientist said. Confident of their discovery, NIOT sent the photographs to the Ministry of Defence (MoD) and the Indian Air Force to corroborate the findings. "They (MOD) confirmed that they were the parts of the An-32, which was lost on July 22 in 2016," the scientist added.
Speaking to ETV Bharat, NIOT Director GA Ramadass said the institute is involved in developing technologies for the exploration and harvesting of ocean resources, both living and non-living. "As a part of non-living resources exploration, we have been developing technologies which can go up to 5000 m water depth. So far NIOT has developed vehicles that are operated from the ships which are unmanned. Now, NIOT is developing a vehicle that can take 3 people to 6 km depth," Ramadass said.
How do AUVs work
Apart from manned and unmanned vehicles, Autonomous Underwater Vehicles (AUVs) are among the latest inclusions in the technology NIOT used in deep sea exploration programs. AUVs are pre-programmed robots that are not connected to motherships with cables and instead function autonomously underwater and explore resources according to the set plan devised before their launch.
"When they (AUVs) surface, we can collect the data and process the sonar images as well as the camera images. We use state-of-the-art acoustic and navigation systems to run the AUV," Director Ramadass said. The was recently acquired by NIOT for exploring polymetallic nodules and hydrothermal sulphites in the Indian Ocean and gas hydrates in the Bay of Bengal.
Polymetallic nodules, also known as manganese nodules, consist of coextensive layers of iron and manganese hydroxides surrounding a core located on the ocean floor. Hydrothermal sulphites, on the other hand, are sulphur compounds that form extensive deposits on the seabed, resembling cobalt crusts.
"While we were using it for our stated purpose, we tested and calibrated this vehicle at a depth of 3500 metres in the Bay of Bengal. When we processed the images, we found that there were some strong reflections which were not from natural objects. When we dived further, we found the objects were debris of an aircraft," Ramadass said.
Another NIOT scientist-in-charge of Deep Sea Technology Group, S Ramesh said because of OME-6000's high-resolution mapping capability, it was able to find the debris. "Since we acquired the AUV, which has high-resolution mapping payloads, we were able to go down to 3,400 metres and do a large area survey and pick up some man-made objects, which turned out to be the debris of An-32," S Ramesh said.
Meanwhile, the OME-6000 also conducted its assigned task successfully and covered the polymetallic nodule mining region in the central Indian Ocean. "We have explored the nodules available. The minerals available are manganese, copper, nickel, and cobalt," NR Ramesh concluded.
The official announcement
According to a statement issued by the Ministry of Defence on January 12, 2024, the search was conducted at a depth of 3400 metres using multiple payloads, including a multi-beam SONAR (Sound Navigation and Ranging), synthetic aperture SONAR, and high-resolution photography.
The MoD also revealed that analysis of search images indicated the presence of debris from crashed aircraft on the sea bed approximately 140 nautical miles (approx. 310 Km) from the Chennai coast.
"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)," the Minister of Defence said in the statement.
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