Raising hopes of getting a clue in locating the missing Coast Guard Dornier, a hydrographic vessel of the Navy has detected intermittent transmission while searching near the last known location of the aircraft.
"INS Sandhyak undertaking sub-surface search, detected intermittent transmission of 37.5 Khz, likely to be from the Sonar Locator Beacon (SLB) of the missing aircraft," a Coast Guard statement said on Saturday.
The transmission was around the position where the Air Traffic Control (ATC) radar had lost contact of the aircraft, it said.
Meanwhile, another patch of multi-coloured sheen of oil in concentric circles was sighted on Friday evening.
"We found this oil patch last evening. This is different from the patch which we found earlier. The sample of oil has been sent to the laboratory for analysis," a Coast Guard official told The Hindu .
While submarine INS Sindhudhvaj was expected to reach the search area late in the evening for further augmentation of sub-surface search, the National Institute of Ocean Technology (NIOT) has also diverted its research vessel 'Sagar Nidhi'.
Reliance India Limited has been approached to extend services of the Multi Support Vessel (MSV) with Remotely Operated Underwater Vehicle (ROV) for underwater operations.
Dornier CG 791 went missing with three officers on board while it was returning from a regular surveillance sortie last Monday evening. The last known location of the aircraft was 16 nautical miles off Chidambaram coast at 9.23 p.m.