OTTAWA — Canada wants in on Iran’s investigation into the plane crash that killed so many from this country. Prime Minister Justin Trudeau has made that clear.

But questions remain about what Canadian officials will be able to do to ensure there is the “thorough and credible” probe Trudeau has called for, even though Iran has invited Canada’s Transportation Safety Board (TSB) to visit the crash site.

What does a “thorough and credible” investigation look like? And will Canada actually get the investigation it wants into the crash that killed 57 of its citizens?

Anatomy of a proper crash investigation

Doug Perovic, a University of Toronto professor who teaches forensic engineering, said one of the first steps in any proper probe is to check the plane’s black boxes — the cockpit voice recorder and flight data recorder. Often they can tell you a lot, he said, including what the pilots were saying and which warnings or technical problems they may have been dealing with.

But in the instance of a missile strike, which Canada, the U.S. and other countries consider likely, the recorders may not tell the whole story.

“In a catastrophic explosion, they’re only going to be good up to the point where data stops being recorded,” Perovic said.

Beyond that, investigators should turn to the “field of debris” — the bits and pieces of the plane scattered about the crash site, Perovic said. By examining pieces of the fuselage, wings and engines, investigators can start to “differentiate between a missile strike, a bomb on board, a drone strike, just a mechanical engine failure.”

David McNair, a former TSB investigator and military pilot, said all pieces of the plane should be carefully collected and photographed before being they are brought to a new location — such as a large hangar — to reconstruct the shape of the plane.

“Quite often you build a full-scale replica cage, and you start attaching those pieces to it to see the breakup pattern and if there's any damage pattern,” he said.

“That’s a long, laborious process” that could take “months and months,” he said.

Perovic added that, at this stage, the investigation should be working to detect explosion patterns, test any residues to determine the chemistry of an explosion, and determining whether any blast came from outside or inside the plane.

Will Canada get the investigation it wants?

Prime Minister Justin Trudeau addressed the nation Thursday afternoon, saying Canada has intelligence that indicates a plane carrying at least 63 Canadians was shot down by an Iranian missile. Trudeau says it is too early to tell whether it was shot by accident or on purpose. (The Canadian Press)

Like it or not, Canada will have to rely on Iran to answer that question, since Canada can only participate to the extent that Iran allows it to, aviation experts explain.

As of Friday night, no Canadian personnel had arrived in Iran even while the government pushes to obtain entry visas for a team of 10 consular employees and two TSB officials, Foreign Affairs Minister François-Philippe Champagne said.

“It starts with the visas, because until and unless we can have our people physically on the ground at the site, at the meetings, we are obviously not in a position to have all the influence we want,” he said.

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“Time is of the essence. Every hour matters.”

Champagne revised the number of Canadian citizens believed to have been aboard the plane to 57 from the 63 initially provided by Ukrainian authorities. He said the new number is based on more careful cross-checking of travel documents, birthdates and other information.

Iran is in charge of the investigation because the plane went down in its territory, according to the Convention on International Civil Aviation, an agreed-upon rule book managed by a special United Nations agency, which includes sections for investigating deadly crashes.

But other countries are entitled to participate, according to the convention, including those where the plane operated and was registered, designed and built. Iran’s state news agency reported Friday that the country has invited plane manufacturer Boeing, the U.S. National Transportation Safety Board and Ukraine to participate in the investigation.

France’s air accident agency will also take part, the Associated Press reported, since the engine was designed by a joint French-American company.

Canada’s participation in the probe is less clear-cut. According to the convention, countries with citizens killed in a plane crash are entitled to visit the scene of the accident, access relevant information, help identify victims, and receive a copy of the final investigation report. But there is no rule to guarantee a direct role in an investigation.

“Their involvement is not the same as, for example, if it had been a Canadian airliner or a Canadian-designed aircraft,” said McNair, the former TSB investigator.

“It does not mean Iran cannot give full privileges to Canada if they so desire, but it’s their call,” he said.

In carrying out a proper investigation, Perovic said the right investigators and specialists need to be available to properly assess flight recorders and wreckage. That means bringing in manufacturers and relevant countries — as Iran appears to be doing — is important.

But he said it is “highly unusual” that Iran would have cleared the crash site of debris 48 hours after the plane went down, as American broadcaster CBS has reported.

“You can’t process that kind of accident scene in two days. That is very disruptive, that is very detrimental to doing a full and complete investigation,” Perovic said.

“It doesn’t necessarily preclude getting to the bottom of this,” he added. “It will just take longer, and maybe some conclusions for some things may not be as definite as they could have been.”

Speaking in Ottawa, Champagne said he is concerned about reports from the crash site, but that “time will tell” whether Iran can be trusted to give Canada and the world the assurance that the investigation is transparent and up to international standards.

“We want full accountability, we want answers to these questions, and the world is watching what the Iranian government is doing,” he said.

With files from The Associated Press and The Canadian Press

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