The navigation equipment on board First Air Flight 6560 may hold the key to why its pilots prepared to land, then aborted the plan, seconds before crashing into a hill near the Resolute airport in Nunavut, killing 12 people.
Brian MacDonald, lead investigator looking into last August's crash for the Transportation Safety Board, said the plane's instruments remain a focus of the review.
"That's one of the key areas we need to unravel," Mr. MacDonald said Friday following the release of an interim report on the investigation.
"What information was the navigational equipment giving to the pilots and how was that being interpreted?"
The pilots' training is also being examined, said Mr. MacDonald, who added it will be several months until a final report on the crash is complete.
So far the investigation has determined the chartered 737 jet was structurally sound and its engines were working.
But the pilots couldn't see the runway because of bad weather. There was drizzling rain and a 90-metre cloud ceiling. Fog limited visibility to less than eight kilometres. Crew had no choice but to land the plane using its navigational instruments.
Mr. MacDonald said his team doesn't yet know why the pilots were preparing to land when the plane was still 1.6 kilometres from the runway.
"How is it the aircraft ended up over there?" he said. "The aircraft was obviously supposed to land on the runway, not end up in the hill a mile to the right of the runway."
The report said the airport had cleared the plane for landing and the crew's final landing checklist was complete. The landing gear was down and locked, and the flaps on its wings were open.
But it was also travelling at 157 knots — a little too fast, Mr. MacDonald said.
He said the plane's flight data recorder shows the plane next attempted a "go-around" to abort the landing.
Two seconds later, it flew into the hill.
Four crew members and a six-year-old girl were among the 12 people who died. Three passengers remarkably survived.
Soldiers preparing for a mock plane crash as part of a military exercise were luckily nearby and had already set up a field hospital.
They had also established their own traffic control tower at the airport to deal with increased plane traffic, Mr. MacDonald said.
He said the investigation has looked into whether the military's control tower and equipment could have interfered with the First Air plane.
"At this point, we have no indication whatsoever it has anything to do with the accident."