The de Havilland Beaver operated by Air Nootka crashed shortly after take-off from a lake northwest of Tofino on Friday.
"They'll be looking at the tree scars to indicate at what angle the aircraft approached its final resting spot... and also at the ground at the bottom of the trees," said Bill Yearwood of the Transportation Safety Board.
Yearwood says investigators plan to use a helicopter to reach the wreckage, and they likely won't arrive until at least noon PT.
Among the dead are Comox, B.C., resident Charles Turner and the plane's pilot, who has not been named.
Turner was on an excursion organized by the Alpine Club of Canada when the group's chartered flight to Gold River went down off Hesquiat Lake.
The excursion's organizer, John Young, is in hospital on Vancouver Island, after he suffered broken bones and third-degree burns on one of his shins.
Young's wife, who spoke with a CBC affiliate on Vancouver Island on Sunday, said her husband told her the plane hit a tree shortly after takeoff, went down nose first, and then flames began spreading through the cabin.
He was able to free himself and another passenger, but not the pilot, said Susann Young.
Two members of the hiking party whose injuries were less severe set up lean-tos to shelter Young and a badly injured woman, and tried to keep them dry and warm while they waited just over five hours for rescuers to find them.
Poor weather has prevented investigators from accessing the crash site, which is in a forested area near Hesquiat Lake, roughly 250 kilometres northwest of Victoria.
Yearwood says small aircraft such as the Beaver involved in Friday's crash don't have flight-data recorders, and investigators have not yet interviewed the survivors.