The sole survivor of a fiery plane crash in northwestern Ontario earlier this month said he tried in vain to unstrap fellow passengers, only managing to pull out the pilot before collapsing in the snow.

Four out of five people were killed after Keystone Air Flight 213 crashed on a lake and burst into flames.

Brian Shead, 36, has been in hospital in Winnipeg since the Jan. 10 crash in North Spirit Lake First Nation.

Speaking for the first time since the crash that claimed four lives, Shead told reporters he was reading a book during the flight with no concern about the upcoming landing or the blustery weather.

"It seemed to be a routine landing. In an instant that changed," he said from Winnipeg's Health Sciences Centre.

'I can't reconcile how my life was spared or why.'— Brian Shead

"I relive it every night. Could I have done something different? [There's] a lot of what-ifs, a lot of questions I'm struggling with."

Shead crawled from the burning wreck, suffering a broken nose, foot and ankle.

"But I escaped with my life," he said. "I had some very good friends in that plane. I can't reconcile how my life was spared or why. An event like this changes a person. I won't take life for granted."

North Spirit Lake is located in remote northwestern Ontario, near the Manitoba border. (CBC)

The four who died are:

• Ben Van Hoek, 62.
• Colette Eisinger, 39.
• Martha Campbell, 38.
• Fariborz Abasabady, the pilot, 41.

All were from Winnipeg except for Van Hoek, who was from Carman.

The plane, an eight-seat Piper PA-31 Navajo operated by Keystone Air, was on its landing approach when it slammed into a frozen lake and caught fire about a kilometre from the runway in the remote community.

"I wish I knew why the horrible incident happened. I do not understand why this crash happened or how it happened and I have no answers," Shead told reporters.

He described being strapped in his chair after the crash and seeing the right wing on fire. He called to his fellow passengers but they were “unconscious and unresponsive to my pleas.”

After trying but failing to unlock their seatbelts, Shead managed to unstrap the pilot and get him away from the craft. He said he likes to think that no one else was still alive and suffering at that point.

"As the fire spread and began to enter the cabin near the rear of the plane I made a final attempt at the pilot's window," Shead said.

"Finally, I was able to release the pilot's seatbelt and haul him out of the plane. I pulled him as far as I could before collapsing in the snow."

The plane had been chartered by Aboriginal Strategies, a Winnipeg company that provides financial management services to First Nations.

The Transportation Safety Board has not yet revealed the cause of the crash.