It was literally a back-of-the-envelope calculation that helped police zero in on the site of the chopper crash which cut short the life of Chief Minister Y.S. Rajasekhara Reddy in the dense Nallamala forests on September 2.

The five passengers of the Bell-430 ignored the rule to switch off their mobile phones but this helped the officials determine a core area for taking up search operations.

Anxiety was mounting among officials as the chopper did not land at Anuppalle of Chittoor district at the expected time of 11 a.m. Panic buttons were pressed by 11.25 a.m. And then commenced the back-end operations for one of the biggest multi-agency search operations the country had ever seen.

As news about the missing chopper broke in the electronic media, there was frenetic activity in intelligence wing offices in Lakdikapul and elsewhere in the city. By 11.40 a.m. sleuths had collected the numbers of the mobile phones carried by the passengers. Apprehending that the copter could have crashed, all units of Greyhounds were ordered to be on standby.

There were six mobile phones on board and three of them were active: 94407-00365 (that of ASC Wesley, CM’s chief security officer), 98499-08530 (CM’s secretary Subramaniam) and 99853-63184 (Pilot Bhatia). The service providers BSNL, Air Tel and Vodafone were contacted instantly. The other three switched-off mobiles were 99480-33333, 90106-45749 and 96666-33555.

While calls were not being answered, officials frantically texted short messages: “Are you all safe? Please convey your location.” The message sent at 11.55 a.m. was delivered to Wesley’s mobile phone at 12.03 p.m. As puzzled officers kept their fingers crossed and waited for a reply at least, others were already tracking the location of the mobile phone, based on the area covered by the cell tower in Pamulapadu village which delivered the SMS. The other two cell towers at Iskala (AirTel) and Parumanchala (Vodafone) too picked up signals from the active mobiles.

“By 12.10, we roughly calculated the area where the SMS was delivered to the mobile,” an officer recalled. By then several computers were downloading Google Earth maps and officials calculating grid references. Simultaneously, the Greyhounds commandos were studying the relevant topo sheets of Nallamala forests. Within 35 minutes, four units [each 100 commandos] were racing down National Highway 7 towards the forests.

“We did some back-of-the-envelope calculations based on phone tower locations which were picking up signals from three active mobiles. With the phone companies providing the sectors from which signals emanated, coordinates were worked out and we pinpointed the search area,” an officer involved in the backend operations recalled.

Every cell tower area has three sectors and the master switch at the exchange would know whenever any mobile phone is moved into its sector. “When we drew the sectors of the three towers, there was an overlapping area which logically indicated the mobile location.” Officials believed that this site could be in the hilly terrain and not in the inhabited plain area, as the chopper would have been noticed.

As coordinates were drawn and redrawn, the first helicopter with a Greyhounds officer scrambled from Begumpet airport at 2 p.m. “Visibility was very poor. Clouds were hanging low and they were so thick that the pilot refused to fly at a low altitude.” By then the Indian Air Force had scrambled some more helicopters from Hakimpet and Yelahanka bases. Two Sukhois too were to join the search mission later. The National Remote Sensing Agency (NRSA) and the NASA of the United States too were roped in but were not of much help.

On the field, the Greyhounds activity too had reached a feverish pitch. Units from as far as Visakhapatnam were rushing to the core search area, roughly a 200 sq. km. spread. “Coordination was a complex operation. We had to avoid friendly fire. Hundreds of civilians too were out searching.”

With the weather remaining inclement, the air search was called off by evening on September 2, but the ground forces continued to move without any rest. The next day morning too, visibility was very low, but mercifully, by 8.15 a.m. the sun shone and the IAF chopper carrying two Greyhounds commandos noticed a burnt patch in the green canopy. As the helicopter hovered, they saw the fuselage and within minutes Assault Commander Vikramjeet Duggal and another commando Qasim Ali winched down and confirmed that it was a no-survivor crash.