Secret documents detailing Canada's plans for responding to a Sept. 11-style attack include a scenario in which military fighter jets are forced to shoot down a hijacked commercial airliner to protect Toronto's CN Tower.

The documents contain precise details about how the military, RCMP and government would determine when to shoot down a hijacked plane, including:

Who makes the decision and how much time that decision would take.

The number of Canadian and U.S. fighter jets on standby.

Where the Canadian jets are located and how long it takes to get them in the air.

When Canadian and U.S. jets are authorized to use force.

The documents were part of a briefing presented to the incoming chief of defence staff, Gen. Jonathan Vance, in 2015. They were obtained by CBC News through the Access to Information Act. The documents contain several sections and full pages that appear to have been marked for redaction, but the information in those sections is still clearly visible.

CBC has chosen not to disclose many of the details in the documents for national security reasons.

"In this case, it sounds to me like a mistake was made," said Vance in an interview with CBC News on Wednesday. "We'll follow up and try and make certain that this sort of thing doesn't happen again."

The release of the documents raises further questions about how the Department of National Defence handles classified information. The department has been under intense public scrutiny since Vice-Admiral Mark Norman was suspended from his position as vice chief of defence staff in early January and was accused of leaking classified data, possibly about shipbuilding.

The documents obtained by CBC News do not relate to the Norman case.

"There are times when material is leaked [by] sources or whatnot," Vance said. "We do not appreciate this at all. Sometimes it can affect how we operate.

"I do believe that it can be injurious to Canada if material is not handled correctly. So it's just part of doing our job well and being a professional organization that we safeguard the classified material that we're suppose to."

He added: "In this case, the correct effort was made to redact it, in as responsive a manner as we could, and I think you'd agree that we tried. You used a process, we used a process, something went wrong. We'll look at it. Fair ball."

Speaking to reporters Wednesday in Calgary, Prime Minister Justin Trudeau said his government takes the "safety and security" of classified documents very seriously and would strive to "do better" when it comes to their management.

"We have very strong systems in place, when those systems break down, or are not followed there are inevitably follow-ups and consequences," Trudeau said. "But we can and have been reassuring our allies throughout that we continue to keep a high priority on the safety and security of confidential documents.

Operation Noble Eagle

The briefing outlines Operation Noble Eagle, a North American Aerospace Defence Command (Norad) operation that was initially developed after the Sept. 11, 2001 attacks in the United States to protect against similar attacks within North American airspace.

Four airliners were commandeered that day by terrorists and turned into passenger-laden missiles aimed at the Pentagon and two towers in New York's World Trade Center. A fourth airliner, thought to be headed for the U.S. Capitol building in Washington, D.C., was brought down by a passenger revolt before crashing in Shanksville, Pa.

RCAF CF-18 Hornets are part of Norad's Operation Noble Eagle to protect North American airspace in the event of another Sept. 11-style attack. (Department of National Defence)

The Canadian document was intended to familiarize Vance with the protocol for dealing with an incident involving a civilian aircraft being used as a weapon in Canadian airspace and outlined what to expect if he were to become the "engagement authority" for the response.

'Weight of responsibility'

"We've got procedures that we practise over and over and over again, to make certain that we can think as clearly as we can in a crisis situation — that we are fully capable of drawing in all the information necessary to be able to make an informed decision — either to recommend an act or actually conduct an act," Vance said.

"There's not a day that I wake up that I don't feel the weight of responsibility, but we're trained to deal with it."

The documents were part of a briefing for chief of defence staff Gen. Jonathan Vance in 2015. Vance said Wednesday the military followed the correct process in releasing the material under Access to Information, but "something went wrong." (Fred Chartrand/Canadian Press)

There are two scenarios in the documents stemming from two orders-in-council. Those are orders given directly by cabinet and in this case were kept secret.

In the first scenario, the order refers to "a terrorist air attack with a clear intent to cause destruction/death aimed at a specific area or ground target in North America from a known terrorist group that we are in an armed conflict with."

That scenario includes consideration of how quickly a decision would have to be made to limit the potential debris field, the area surrounding a crash or explosion that sustains damages and contains pieces of wreckage, in a densely populated area.

The second case involves a scenario in which the military would assist law enforcement agencies such as the RCMP and would include "a more traditional hijacking scenario where a disgruntled individual may want to take out his aggressions on a company headquarters or specific person(s), or even the government."

The details included in the briefing also reveal how and when the United States would be involved if an attack occurred, including when the United States would be called and how they would be able to act in Canadian airspace.