The search for the missing Dornier aircraft of the Indian Coast Guard has entered its fourth day on Friday.
Fifteen ships belonging to both the Coast Guard and the Indian Navy are a part of the search mission, in addition to the advanced Boeing Poseidon P81 surveillance aircrafts, said reports.
The aircraft CG-791 was on a routine surveillance off the coast of Chennai on Monday evening when it lost contact.
As per reports, the search operation teams detected an oil spill near the probable area of crash and the water samples had been sent off by the Indian oil corporation to determine whether the oil was that of aviation fuel or diesel used by the fishing boats.
Coast guard officials (east region) said the crew consisting of two pilots and one observer were highly experienced. The aircraft was inducted last year into services.