The court of inquiry set up by the army to probe Friday’s helicopter crash in Arunachal Pradesh that killed all five persons on board will “focus” on a “Mayday call suggesting a technical or mechanical failure”.

A Mayday call is a distress/SOS call conveying an emergency situation.

The army’s advanced light helicopter (ALH) crashed during a routine sortie near Migging, about 25km south of Tuting, in Upper Siang district bordering China, around 10.43am on Friday.

An army statement issued on Saturday said: “Prior to the crash, the Air Traffic Control (ATC) had received a Mayday call suggesting a technical or mechanical failure. This will form the focus of the Court of Inquiry, which was immediately constituted to investigate the causes of the accident.”

The chopper, manufactured by Hindustan Aeronautics Limited and inducted into the army in 2015, had taken off from Likabali in Assam.

The statement added: “It is reported that the weather was good for flying operations. The pilots had more than 600 combined flying hours on ALH-WSI (Weapon Systems Integrated) and over 1,800 service flying hours between them.”

The deceased army personnel in Friday’s crash were Major Vikas Bhambhu and Major Mustafa Bohara (both pilots), Aswin K.V., Biresh Sinha and Rohitashva Kumar.

“Immediate joint search operations with teams from the army and air force located the crash site, where the terrain is extremely challenging in terms of hills with steep gradients and thick jungle. Four of the bodies were recovered on Friday and one on Saturday,” Tezpur-based defence spokesperson A.S. Walia said.

Air crashes in the frontier state are mostly attributed to inclement weather.

At least nine chopper crashes have taken places in Arunachal Pradesh since 2010, making the state a huge challenge for even the most experienced pilots because of sudden changes in weather and strong windy conditions in a difficult mountainous terrain.

Friday’s crash was the second involving an army chopper since October 5 when a Cheetah helicopter of the army crashed during a routine sortie in the Jemeithang circle of Tawang district. One of the two pilots died.

Tawang borders China, which considers Arunachal to be a part of South Tibet. An MI-17 chopper had crashed in Anjaw district last year but there was no loss of life.

Rescue operations under way after a Cheetah helicopter of the Indian Army crashed in the Tawang district of Arunachal Pradesh on Wednesday morning. PTI picture