As the arduous operation to trace the IAF's missing AN32 aircraft with 29 people on board stretched into the third day on 24 July, the search and rescue team is now seeking satellite imagery to find any clue of the plane that lost contact over the Bay of Bengal.
"There is no sign of the plane as yet," a senior defence official said.
At least 18 navy and coast guard ships including a submarine, and eight aircraft like P 81, C 130 and Dorniers are involved in the round the clock operation to search for the Port Blair-bound transport plane which went missing after it took off from the Tambaram air base near Chennai at 8.30 am on 22 July.
Inclement weather was posing a major challenge in the operation. The authorities are now seeking satellite imagery of the area.
"The search operation is continuing on a 24-hour basis and all resources at disposal are being used.
"We have also sought satellite information," Eastern Naval Command chief Vice Admiral HCS Bisht said in Vishakhapatnam.
"The depth of water there is about 3,500 metres and in some place it is even more. As the depth increases, challenges also increase," he said, adding that the weather was rough and it was raining.
He said the family members are being updated on a regular basis.
Meanwhile, airforce authorities have lodged a formal complaint with Tamil Nadu police over the missing AN-32 aircraft.
"We have received a complaint that Air Force's AN-32 transport aircraft has gone missing," a senior police official said.
"The complaint was lodged last night with Selaiyur police," he added.
"The complaint says that 29 personnel on board AN-32 and the aircraft have gone missing. Among the missing personnel is one person from Tamil Nadu," the official told PTI.
The complaint has been lodged for legal purposes. A similar complaint was filed when Coast Guard's Dornier aircraft went missing last year. The wreckage of the CG Dornier aircraft and bodies of its crew were later found off Cuddalore in Tamil Nadu.
The Russian-made workhorse made the last radio contact at 0846 hours, 16 minutes after take off, on Friday.
Worries mounted for the authorities as time was running out and no positive signals emerged from the operations.
Defence Minister Manohar Parrikar yesterday undertook an aerial survey to personally monitor the search and rescue operations.