With no signs of wreckage of the Indian Coast Guard's aircraft that went missing on Monday night and no signals from the plane or from the crew's cellphones, the search for the aircraft has been intensified, the Coast Guard said. In a statement issued on Wednesday, the Coast Guard said the search operation for the Dornier aircraft is being augmented with two more naval ships with sonar to facilitate sub-surface search deployed in the area. The coastal security agency said 15 highly-specialised Coast Guard/Naval ships and several other patrol boats of coastal security group were involved in the search operation. Air sorties have been carried out for 40 hours to locate the missing aircraft. Asked about the mobile phone tower signals from the cellphones of the three-member crew, a Coast Guard official told IANS that no such signals were received. The aircraft with three crew members aboard, all in their 30s, went missing near Karaikal in Puducherry on Monday night. The crew comprised Deputy Commandant Vidyasagar, piloting the aircraft, his co-pilot and deputy commandant M.K. Soni, and navigator/observer Subash Suresh. The missing aircraft was deployed for surveillance along the Tamil Nadu coast and Palk Bay. It took off from Chennai airport on Monday at around 6.00 p.m. for a surveillance sortie. But it did not return. An official statement issued on Tuesday said the last contact with the aircraft was made at 9.00 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. A Coast Guard official told IANS on Tuesday night that no signal including sonar has been obtained. "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. With IANS