Director General of Coast Guard Vice Admiral H C S Bisht held a meeting with top officials in Chennai to review the operations in which a total of 15 ships have been engaged now.
"He reviewed the search operations. We briefed him about the ongoing search activities. He has given us directions and we have beefed up search operations," Inspector General S P Sharma, Commander, Coast Guard (East), Chennai, said.
The Coast Guard, Navy and state Coastal Security Group personnel, along with 15 highly specialised ships, besides boats, are engaged in the search operations that have gone beyond 40 hours.
"A submarine has also been deployed today to trace any debris that might have sunk," Navy sources said in New Delhi.
Meanwhile, Bisht also met the family members of the missing crew -- Pilot, Deputy Commandant Vidyasagar, Co-pilot Deputy Commandant M K Soni and Navigator Deputy Commandant Subash Suresh, a Coast Guard statement said.
No debris or wreckage has yet been located, it said.
Coastal Security Group DSP P Ramamurthy told reporters in Cuddalore that the search was being conducted in about a 70-km area between Nallavadu-Pichavaram coastal areas.
More than 200 officers, police personnel and over 300 fishermen were searching for the aircraft, he said.
The Coast Guard statement said 15 CG/Naval ships and several other patrol boats of Coastal Security Group were involved in the search being undertaken in the sea off the coast between Cuddalore and Puducherry.
Further air sorties by search aircraft have been undertaken to locate the missing plane and its three crew members, it said.
Two more Naval ships equipped with sonar detection facility were being deployed for the operations, it said.
The aircraft CG-791, which was inducted last year, went off the radar at 9.23 pm on Monday during a routine surveillance mission along the state coast and Palk Bay after it took off from the Chennai station.
A report from Puducherry quoting Coast Guard District Headquarters Commandant M Somasundaram said search operations had also been intensified at the site where a fisherman had claimed noticing a burning object falling into the sea off Reddychavady/Krimambakkam villages between Puducherry and Cuddalore.