Autumn Veatch told NBC News there was zero visibility before the Saturday accident, and then “it was all trees and then it was fire.”
Authorities have said the plane entered a cloud bank before the crash.
Veatch said after the crash her step-grandparents, Leland and Sharon Bowman, were trapped.
She said she couldn’t get to Sharon Bowman but burned her hand trying to free Leland.
Before she fled she says she told the Bowmans that “I loved them and that it would be OK.”
The 16-year-old Veatch survived the impact and was able to hike to safety.
Veatch said Leland and Sharon Bowman were alive and screaming as the aircraft burned: “I was trying to pull them out and I just couldn’t do it. There was too much fire and I’m a small person … I was trying, but there was no point – it’s just not happening.”
Two bodies were recovered from the crash site, but authorities said that the fiery crash has made official identification difficult.
Leland Bowman was flying Veatch from Montana to Bellingham, Washington. After being hospitalised Veatch returned home to Bellingham late on Tuesday.
It took her about two days to find help after the weekend crash that left her bruised and singed.
She had to make her way down a steep slope and follow a creek to a river. She spent a night on a sand bar and sipped small amounts of water.
She told NBC she fell down a cliff but kept going.
“And I just got this surge of willpower and was like there’s no way I can die without hugging somebody again,” she said.
She followed the river to a trail, and the trail to a highway where two men driving by stopped and picked her up Monday afternoon, bringing her to a general store in tiny Mazama, near the east entrance of North Cascades National Park.
Okanogan County Sheriff Frank Rogers has said she and her relatives were flying a Beechcraft A-35 from Kalispell, Montana, to Lynden, Washington, when it struck the trees, plummeted to the ground and caught fire.
Officials will use dental records to confirm the identities of the bodies recovered, which could take about a week, Skagit County Deputy Coroner Matthew Sias said in a phone interview with The Associated Press.
Terry Williams, spokesman for National Transportation Safety Board, said the agency is investigating the accident on Thursday but had not reached the site yet because “the wreckage was located very recently.”