The government is seeking help from American defence forces to ascertain whether their satellites had picked up any signal before the disappearance of the plane, Defence Minister Manohar Parrikar said in Rajya Sabha on Friday.
"At the time of disappearance, the aircraft was on secondary/passive radar and there was no SOS or transmission of any frequency. It just disappeared so that is the worrying part," Parrikar said.
"It is total blank. There was not even a single signal recorded. That is the reason we are contacting American defence forces to ascertain whether their satellites picked up any signal," the defence minister said.
"Besides our own satelleite imagery, we have asked the US for their imagery for the detection of emergency frequency to space based assets. Foreign countries we have already asked. I only hope that our efforts succeed," he added while replying to queries whether foreign help has been sought.
The defence minister said the possibility of a sabotage in the mysterious disappearance of AN-32 aircraft was "comparatively very less".
All types of techniques are being used to locate the aircraft, he said while replying to clarifications sought by members on his suo motu statement on the disappearance of the aircraft on July 22.
As members expressed concern and raised questions over how the plane went missing, he said, "I can't speculate because we are searching for it and I will not like to speculate. But I can say only this much. The possibility, although we are checking all angles, of any sabotage is comparatively very less because they have standard operating procedures."
While sharing the concern of the members, he gave details of the operation being carried out for the last one week in trying to locate the plane, carrying 29 people, which went missing during a flight from Tambaram in Tamil Nadu to Port Blair.
"I appreciate anxiety of members. I am also disturbed at the sudden disappearance of the plane. I have spoken to several experts and former air chiefs who were also puzzled by the sudden disappearance," Parrikar said.
Queried about the age of the aircraft, the Defence Minister said it was "almost as good as new aircraft".
Elaborating he said, "I don't know exact age but it is well within lifetime. It has undergone first overhauling. Lot of replacement has been done.... They are considered as one of the safest aircraft."
He said the accident rate of Indian Air Force is 0.23 out of 10,000 hours of flying against the global rate of 0.023 and assured the House that maximum efforts would be made to ensure that the mishaps come down.
"If aircraft is not fit for flying we don't fly it. We have decided to check up whether we can improve the signalling system," he added.
About the missing aircraft, Parrikar said that after the first overhaul, the plane had already done 279 hours and the pilot was experienced, having put in 500 hours on this route.
The Defence Minister, who had made suo motu statement on the plane's disappearance in both Houses of Parliament on Thursday, said, "Let us hope that we track it down. I can assure that maximum efforts will be taken."
Sharing details of the search operation so far, he said 10 Indian Navy ships as well as submarine 'Sindhudhwaj' are carrying searches and "virtually checking up everything".