The ROV is with NIOT vessel Sagar Nidhi. "It is currently being prepared and minor repairs being carried out and should be ready within this week," an office told The Hindu.

A Remotely Operated Vehicle (ROV) with a robotic arm will descend deep down to the sea floor of the Bay of Bengal to depths of up to 3.5 km later this week to scan suspected large objects and confirm whether they belong to the missing An-32 transport aircraft of the Indian Air Force.

The An-32, took off on a routine weekly courier flight from Chennai to Port Blair on July 22, 2016 at 8.30 a.m. with six crew and 23 personnel but never reached the destination. Massive search efforts have so far yielded no trace of the aircraft and the search gradually moved underwater to scan the sea bed.

Two research vessels, Oceanographic vessel Samundra Ratnakar of the Geological Survey of India and Sagar Nidhi of the National Institute of Ocean Technology (NIOT), are leading the underwater search. “They are capable of sonar search up to the depths at which the aircraft is supposed to be and have been mapping the sea bed,” one official said.

With no incoming signal from the aircraft this is practically a “blind search,” one official said. Over the last two weeks several hundred linear objects had been identified in the scan, which could potentially be parts of an aircraft, spread over several square miles on the sea floor.

The real confirmation is only by visual examination and it is not practically possible to check every object. So they were further narrowed down for immediate examination. “We have identified about 30 objects and the ROV will be lowered down to verify them in a couple of days, a senior defence official said last week.

The ROV is with NIOT vessel Sagar Nidhi. “It is currently being prepared and minor repairs being carried out and should be ready within this week,” one officer monitoring the situation told The Hindu.

An ROV is a small unmanned vehicle controlled from a ship on the surface with a long cable. “It also has a robotic arm which can be used to pick and move things,” the officer added.

Another officer explained that in the Bay of Bengal the maximum depth of the sea floor is 3.5 km and the cable to which the ROV is tethered too will be as long with another 10 per cent margin. The scanning process, however, is a long and tedious one. According to officials the ROV takes close to 24 hours to scan a square mile.

Officials suggest caution

While the leads look promising, there is no certainty as of now that the objects belong to the aircraft.

“Echoes are just electronic picture. It can be anything. It has to be confirmed by physically verifying it. It cannot be confirmed until we find some aircraft part,” defence sources said.

The sources explained that the sea floor is littered with various objects particularly after the Indian Ocean tsunami and the leads which looked credible are being pursued. “While we can make the shape of the objects from the echoes we cannot distinguish what it is,” they added.