Investigators expect to know within weeks how military aircraft crashed but why will take a lot longer

Teams of investigators looking for answers in two deadly Canadian military crashes will likely have a preliminaryunderstanding of what wentwrong within weeks of beginning their work, according to the colonel overseeing thecases.

But finding an explanation for why things went wrong will be a far more complex task.

"We can generally arrive at what happened, or what went wrong, after about a month," said Col. John Alexander,the Armed Forces' director of flight safety.

"The more difficult challenge becomes understanding why."

Two flight safety investigations run by theRoyal Canadian Air Forceare looking into two crashes in as many months.

An eight-member team arrived from Ottawa in Kamloops, B.C. on Monday, where aSnowbirdsjetcrashed into a residential neighbourhood shortly after takeoff.Capt. Jenn Casey, a public affairs officer for the aerobatics team, was killed. The pilot is expected torecover from his injuries.

It happened less than three weeks after aCyclone helicopter went down in the Ionian Sea on April 29, killing all six people on board. The remains of two Armed Forces members on boardhave been recovered,while four others are missing and presumed dead.

The investigationswill notdetermine fault or culpability for either crash. They are done solely topreventfuture crashes from a flight safety perspective, according to the government.

Alexander could not comment specifically on eitherinvestigation but explained how such investigations are donein an interview with CBC News on Wednesday.

Evidence, data, human factors play a role

Hesaid investigators begin their work in the field,collecting as much perishable evidence as quickly as possibleartifacts like oil and fuel samples, whichwould be ruined or lost if left uncollected too long.

That work is easier in Kamloops, where the red-and-white remains of the CT-114Tutor lie scattered acrossresidential front lawns.

It is far more complex off the coast of Greece, where the fuselage of theCH-148 Cyclone helicopter rests under 3,000 metres of seawater. Canadian investigators are working with the U.S. navy to recover the wreckage within the week.

Alexander said investigators' most "arduous" work usually begins after the evidence-gathering. The officers will siftthrough "mountains" of flight data, witness accounts, mechanical reports and other information pertaining to the crash.

Combining evidence with data, he said,should give investigators ageneral idea of what happened within 30 days.

In the case of a fatal crash, the preliminaryfindings are passed tothe familiesof the deceased before a briefsummary is made public.

"[It's] what we call a 'From the Investigator,'" Alexander said. "It's typically a one-pager that will provide the facts of the scenario as we understand it."

In the months that follow, investigators will analyze thehuman factors. Teams will look at how personnelinvolved reacted to the situation, and whether those reactions contributed to the crash.

"That gets into some very complex understandings of the human factors, the decision-making processes, how people understood the environment around them," said Alexander.

Thefinal report, which could take up to a year, recommends preventative measures to the higher chain of command within the military and directly to the Ministry of Defence.

The final recommendations, which will come from Alexander,will be posted publicly online.

"It's ultimately the responsibility of the ministers to accept those recommendations for implementation or not," he said.

The investigatorsare themselves experienced operations, air crew, engineers andmedical officers. Alexander said teamsfeel a kinship withthose involved in the cases on which they work.

"Obviously, in the military, we would like to think of ourselves as one large family," said Alexander, who has 30 years' military experience and has flown the same kind of Tutor jet that went down in Kamloops.

"As with any large family, one of the things we want to do is do justice to the memory of our friend. That is done by ensuring that we get to the bottom of an investigation."

Alexander said the flight safety team works as an independent body and can share resources with other organizations such as the Transportation Safety Boardand theNational Research Councilover the course of an investigation.