A CH-146 Griffon Helicopter from 408 Tactical Helicopter Squadron, during tactical training for Afghanistan. (Canadian Forces) A helicopter crash in Afghanistan that killed three soldiers, two of them Canadian, apparently occurred when the chopper clipped a security wall while trying to manoeuvre in a blinding cloud of dust, The Canadian Press has learned.

Sources familiar with the tragedy said the Griffon CH-146 smashed to the ground and burst into flames.

Master Cpl. Patrice Audet died in Afghanistan on Monday in a helicopter crash in Zabul province, about 80 kilometres northeast of Kandahar city. (DND)The crash on Monday killed Master Cpl. Patrice Audet, 38, of Montreal, a flight engineer, and Cpl. Martin Joannette, 25, a gunner from St-Calixte, Que. British Capt. Ben Babington-Browne, 27, from the 22 Engineer Regiment, Royal Engineers, was also killed.

Three other Canadians aboard were hurt, one seriously.

It is common in parched southern Afghanistan for helicopters landing or departing at operating bases to become engulfed in the dust whipped up by their rotors.

With a second Griffon in the air nearby, the pilot lifted off and struggled to orient the helicopter in the whirled-up dust storm compounded by gusty conditions that cut visibility essentially to zero, the sources said.

The helicopter veered too close to the reinforced security perimeter, which is designed to ward off suicide bombers and direct fire from insurgents.

Cpl. Martin Joannette also died in the helicopter crash, which military officials said was not caused by enemy fire. (DND)Military authorities have declined to talk officially about the circumstances of the crash as an Air Wing investigation has been launched.

They will only say publicly that enemy action had been ruled out, despite Taliban claims of having shot down the craft.

The sources said the chopper that was already in the air may have contributed to the adverse conditions surrounding the crash. They stressed that the formal probe may yet uncover other factors that led to the tragedy.

Flight picked up British soldier

The two pilots in the downed chopper survived. Canadian military rules bar publication of the names of deployed flight crew.

The two choppers, part of Canadian Helicopter Force Afghanistan based at Kandahar Airfield, had flown to a remote American forward operating base in the Tarnak va Jaldak district of southwest Zabul province, about 80 kilometres northeast of Kandahar city.

The flight, just outside Canada's normal area of operations in Kandahar province, was to pick up the British engineer.

Under normal operating protocols — essentially for reasons of security — the Griffons fly in pairs, allowing them to keep an eye on each other. The crews depend heavily on sight to know where the other is at any given moment, and the flying itself also relies to a significant degree on visual orientation.

"We feel mixed emotions of pain and frustration," Lt.-Col. Marc Bigaouette, commander of the helicopter force constituted little more than six months ago, said Tuesday.

"The incident … was not expected."

Like other military officials, Bigaouette refused to discuss the circumstances of the crash, citing the investigation.

The bodies of Audet and Joannette were expected to be returned to Canada on Thursday.

Their deaths brought to 124 the number of soldiers killed since Canada joined the international stabilization effort in Afghanistan in 2002.