Hopes of finding the Indian Coast Guard's missing Dornier aircraft suffered a setback on Thursday with the oil test report turning out negative, said an official.
Speaking to IANS, a Coast Guard official said: "The oil test report result is negative. The search is continuing."
Some oil was found floating in the Karaikal sea - an area where the search was being conducted - and sent for tests but the test report held that the oil sample does not belong to the missing aircraft.
The intensive search for the aircraft, with a three-member crew, that went missing near Karaikal in Puducherry Monday night continued for the third day on Thursday with no signs of the wreckage, a Coast Guard official told IANS.
He said a submarine was also deployed in the search operation.
The Coast Guard has sought the Indian Space Research Organisation's (ISRO) help to locate the missing aircraft with the help of its satellites.
An ISRO official said if the aircraft has the search and rescue beacon, then their satellites would be able to pick up the signal.
It is not known whether the missing aircraft has the necessary instrument to send out distress signals.
The coastal security agency on Wednesday said 15 highly specialised Coast Guard/naval ships and several patrol boats of Tamil Nadu Police's Coastal Security Group were involved in the search operation. In addition, naval submarine INS Sindhudhwaj and survey ship INS Sandhayak, which is equipped with sonar, have also been deployed for the search.
Air sorties too have been carried out to locate the missing aircraft.
An official statement from the Coast Guard on Thursday said further aerial search by coastal security groups using their paramotors will also be undertaken along the marshy and mangrove areas not accessible by sea.
Asked about the tower signals of cellphones of the aircraft's crew, a Coast Guard official told IANS that no such signals were received.
The missing aircraft was deployed for surveillance along the Tamil Nadu coast and Palk Bay. It took off from Chennai airport around 6 p.m. on Monday for a surveillance sortie but did not return. The crew comprised Deputy Commandant Vidyasagar piloting the aircraft, his co-pilot and Deputy Commandant M.K. Soni and navigator/observer Subash Suresh, all in their 30s.
An official statement issued on Tuesday said the last contact with the aircraft was made at 9 p.m. on Monday.
The last known location of the aircraft, as per Trichy radar, was off Karaikal in Puducherry, where it was tracked till 9.23 p.m., 95 nautical miles south of Chennai.
"The aircraft was the latest induction in the Coast Guard inventory in 2014 and was being flown by highly experienced crew," an official statement said.
The latest incident comes months after a Dornier-228 of the Indian Navy with three crew members went down in the Arabian Sea off the coast of Goa.
