Nine of Canada's top military leaders were on board a government jet that nearly collided with a passenger airliner over British Columbia earlier this year.

RCMP officers are seen outside a CC-144 Challenger jet. (CBC)The senior military commanders were all travelling together in a Canadian Forces CC-144 Challenger flying eastbound on April 24 to Ottawa from Vancouver. Over the skies of British Columbia, the aircraft had a harrowing near-miss incident with an Emirates Boeing 777 flying from Los Angeles to Dubai.

The military, which operates the fleet of Challenger jets, would not disclose the identities of the passengers on the flight when the incident first came to light early last month.

But CBC News has confirmed that Lt.-Gen. Andrew Leslie, head of the army, Lt.-Gen. Angus Watt, chief of the air force, as well as the former head of the navy, Vice Admiral Drew Robertson were among the senior brass on board the jet.

Both aircraft were cruising at about 11,200 metres (37,000 feet) when their collision avoidance systems sounded, indicating the two planes could slam into each other.

The Emirates plane, which can carry up to 266 people, quickly climbed, while the government jet performed a dive. The planes passed each other within 213 metres (700 feet) vertically, breaking the "safety bubble" of 300 metres (1,000 feet) around aircraft.

Jets used to shuttle VIPs in secrecy

The Challenger fleet is used to fly Canada's high-level officials, including the prime minister and Governor General, in utmost security. The incident has raised questions as to how the military could allow its top leadership to fly on the same flight.

The Department of National Defence said it doesn't have a policy governing how commanders travel. But most large corporations have policies that limit the number of executives that can travel together.

"You cannot have a group of C-level CEOs and CFOs travelling together," said Tanya Racz, of the National Business Travel Association, in an interview from Calgary. "It would impact companies' operations if anything unforeseen were to happen to them."

But in the corporate world, travel budgets can be substantial, making it easier for CEOs to travel separately. In contrast, public agencies like the Canadian Forces are often constrained by fiscal limitations, said Philippe Lagassé, who researches foreign and defence policy and teaches at the University of Ottawa and the Royal Military College of Canada.

"Were you to demand that they all travel separately, the cost would be significant and it would perhaps be seen as a sign of government waste, something the CF definitely wants to avoid," he told CBC News.

The government's fleet of Challenger jets is reserved for high-level officials, including the prime minister and Governor General, as well as foreign dignitaries who use it to fly in utmost security.

The prime minister is not prohibited from flying with another Canadian leader. Over the years, Stephen Harper has travelled with high-ranking cabinet ministers and defence staff.

DND said it has no plans to review the lack of policy concerning how the military elite travel.

The Transportation Safety Board is investigating the April incident.

With files from Melanie Nagy