The massive search operation to locate the chopper carrying Andhra Pradesh Chief Minister Y S Rajasekhara Reddy is centred around the coordinates of the two mobile phones which were emitting signals even after the Bell 430 helicopter went missing.

The Indian Express has learnt that two mobile phones did ring when efforts were being made to establish contact with the passengers. While there was no response, authorities were able to locate the nearest transmitters: a BSNL tower at Palunapadu and an Airtel tower at nearby Iskala. Both are in the dense Nallamala forest area near Nandyal which falls on the chopper’s flight path from Hyderabad to Chittoor.

After being cautious for the first couple of hours amid conflicting reports over the incident, the Centre swung into action late afternoon asking the Air Force to go all out in their search mission. Home Minister P Chidambaram had a conversation with US Ambassador Tim Roemer this evening to discuss how the US could help. “The Ambassador has been in touch with the Home Minister several times through the evening. He has offered US help and assistance,” said a US Embassy spokesperson.

It’s learnt that talks with the US were on possible help from its satellittes to try and locate the signal of the emergency response transmitter in the Bell chopper. Its on-board transmitter sends out a signal at a known frequency of 121.5 and 243 MHz. It’s by international agreement that all remote sensing satellites pick up any signal on this frequency and relay the coordinates. While ISRO satellites make rounds after some hours, India was looking to obtain US help in case one of its many sateliites picks up the signal. This transmitter is set off the moment there is an accident.

... contd.