Men and machines launched a search operation of an unprecedented scale at dawn on Sunday to locate a helicopter carrying Arunachal Pradesh chief minister Dorjee Khandu that disappeared Saturday morning.
"Police patrols and villagers along the routes the chopper could have taken had been searching throughout the night. But a more organized terrestrial operation involving police, army, Sashastra Seema Bal and Indo-Tibetan Border Police began at sunup today (Sunday),"said Arunachal Pradesh DIGP Robin Hibu.
Search teams from neighbouring Bhutan have also launched rescue operation in seven districts of that country, sources said.
The four-seater Pawan Hans chopper carrying Khandu and four others including Yeshi Lamu, sister of Tawang MLA Tsewang Dhondup, and security officer Yeshi Choddak, went missing 20 minutes after taking off from Tawang at 9:55am on Saturday.
Around 2pm, Arunachal governor JJ Singh and officials said the chopper had been located in adjoining eastern Bhutan and that Khandu, 56, was safe. But Bhutan denied any Indian helicopter had landed within its territory.
Army and Indian Air Force helicopters had on Saturday tried to make an aerial survey of the routes the missing helicopter could have taken. But bad weather made them abandon their search operations.
While the security forces and locals began combing the areas where the helicopter could have landed or crashed, Pawan Hans and IAF choppers readied for aerial scouting early Sunday morning.
Apart from ground patrol and helicopter surveillance, the search techniques involved included human sightings, use of thermal imaging devices mounted on aircraft, remote sensing agencies and unmanned aircraft.
The Tawang sector and other high-altitude areas of Arunachal Pradesh are considered an aircraft graveyard. At least 200 World War II aircraft vanished while flying over this frontier state in the 1940s. Between November 1997 and 19 April this year, 40 civilians and security personnel have been killed in four major crashes in the state.