The Indian Air Force on Thursday informed the families of those on-board the missing Antonov-32 aircraft that they have been presumed dead and that search operations have ended. Joint search and rescue operations, involving the IAF, Indian Navy and Indian Coast Guard, failed to secure any leads off the Chennai coast, The Indian Express reported.

The aircraft had 29 people on-board when it was reported missing over the Bay of Bengal on July 22. It had taken off from Tambaram air base in Chennai and was headed to Port Blair.

In a letter, titled Presumption of Demise, to the families, the Indian Air Force authorities said a Court of Inquiry was conducted to "examine the available evidence and establish the possibilities of survival of the aircrew and passengers," India Today reported. The inquiry, the letter says, concluded that it was "unlikely that the missing personnel would have survived the accident." The relatives concerned have been asked to sign the "certificate of presumption of death" to initiate compensation proceedings.

The letter also informs the families that the Indian Air Force "spared no efforts whatsoever in trying to locate the aircraft and the missing personnel. No fewer than 201 search and rescue sorties were undertaken." It said that data from international agencies also failed to offer any leads.

Family members of the victims were persistent in requesting for information about the search effort. The difficulty level of the search operation was high because the aircraft did not have an underwater locator beacon, which allows it to be tracked in the ocean. A Geological Survey of India vessel recently discovered debris, possibly belonging to the missing Indian Air Force flight AN-32, during a deep-sea operation.