Signals possibly emanating from a Coast Guard Dornier aircraft, which went missing off the Tamil Nadu coast five days ago, were picked up by a naval survey ship on Saturday.
INS Sandhayak, which is participating in the sub-surface search, detected intermittent transmission on 37.5 Khz, likely to be from the sonar locator beacon (SLB) of the missing aircraft, an official statement from the Coast Guard said.
The transmission from the beacon was from around the same position where the air traffic control lost contact with the aircraft at 9.23pm on Monday.
Defence ministry spokesperson Sitanshu Kar tweeted that a multi-coloured sheen of oil in concentric circles was sighted, in a development that indicated oozing of oil. He added the sample of oil has been sent to the laboratory for analysis.
On Thursday, a similar sample tested by IOC turned out to be only sea water with no traces of oil in it.
Authorities sought the services of a multi-support vessel with remotely operated underwater vehicles for underwater operations, official sources said. In all, 10 Coast Guard and navy ships and two aircraft are carrying out search operations.
Naval submarine INS Sindhudhvaj is likely to arrive in the area late on Saturday for further search operations. Sagar Nidhi, the research vessel of the National Institute of Ocean Technology (NIOT), has also been diverted to the area.
In addition to this, Reliance India Limited has been approached to extend services of its Multi Support Vessel(MSV) with Remotely Operable Underwater Vehicle (ROV) for underwater operations.
The Dornier aircraft went off the radar during a routine surveillance mission along the state coast and Palk Bay after taking off Chennai. The aircraft’s last known position was near Karaikkal.
The fate of its crew – deputy commandant Vidyasagar who was piloting the aircraft, co-pilot and deputy commandant Subash Suresh and navigator MK Soni, all in their 30s – is still unknown.
This is the second incident this year involving a Dornier aircraft of the armed forces. In March, two crew members of a Dornier aircraft of the navy were killed when it crashed off the Goa coast.