Chennai, June 13: The Indian Coast Guard officials said on Saturday that INS Sandhyak, undertaking sub-surface search for the missing Dornier, has detected intermittent transmission of 37.5 Khz, likely to be from the Sonar Locator Beacon (SLB) of the aircraft.
An official said that for the past 110 hours various naval and ICG assets have been conducting non-stop search operations.
The transmission has been detected around the same position where the Air Traffic Control radar had lost contact with the aircraft.
ICG says a multi coloured sheen of oil in concentric circles was sighted which indicated oozing of oil. The sample of oil has been sent to the laboratory for analysis.
To augment the search operations, the National Institute of Ocean Technology has diverted its research vessel Sagar Nidhi.
The officials have sought the help of Reliance to rope in their Multi Support Vessel (MSV) with Remotely Operated Underwater Vehicle (ROV) for underwater operations.
On Friday, the ICG officials said that they had intensified the search operations to locate the aircraft.
The aerial search mission is being undertaken by Coast Guard Dornier and Indian Navy's long range maritime reconnaissance aircraft P8I.
The TN police and Coastal Security Group are also part of the search and rescue missions in the last five days.
Around 12 Coast Guard and naval ships have been summoned for duty along with a number of patrol boats.
The ships included ICG Sarang, Vigraha, Ameya, Abheek, Raj Tarang, C-415, IC-119, IC- 120, INS Khukri, Chetlat, Coradivh and Carnicobar.
Adding teeth to the search operation were submarine INS Sindhudhwaj and survey ship INS Sandhayak, both being equipped with advanced sonars.