The Mi-17V-5 helicopter which crashed in Tamil Nadu with Chief of Defence Staff General Bipin Rawat and 13 others on board is the latest twin-engine version of the Russian-made Mi-17 transport helicopter and is used regularly for high-altitude operations.

The Mi-17V-5 helicopters are extremely reliable and are the workhorses of the Air Force, according to defence officials who have flown the aircraft.

They described it as a "very reliable, safe, stable, and large" helicopter that is also used to ferry VIPs, including the President and the Prime Minister.

The defence forces have a large fleet of these helicopters that were purchased and inducted between 2013 and 2018. 

Read Also: Helicopter with Chief of Defence Staff General Bipin Rawat, 13 others on board crashes in Tamil Nadu

There have been no major accidents involving the helicopter apart from a single accident in Jammu and Kashmir in February 2019, the day after India conducted an aerial strike in Pakistan's Balakot in the aftermath of the Pulwama terror attack.

The crash has puzzled experts, who said the flight from Sulur to Wellington did not involve complications.

The Indian Air Force Chief Air Chief Marshal Vivek Ram Chaudhary has himself flown down to the crash site to get a first-hand report of the tragic accident. The Indian Air Force has already ordered an inquiry into the crash.

Four people are dead and another four who survived, have been taken to a hospital. It is believed that there were 14 people on board, including the chopper's crew and passengers.

According to information put out on the website of Russia’s Rosoboronexport, the helicopter is designed to "carry personnel, cargo and equipment inside the cargo cabin or on an external sling, drop tactical air assault forces and reconnaissance and sabotage groups, destroy ground targets and carry the wounded".

Its armament system includes unguided rockets (up to 80 S-8 80mm unguided aerial rockets), cannons (suspended pods with 23mm cannons and 250 rounds each) and small arms.