The converted Boeing 737 passenger plane went down over Fitzgerald River National Park in WA's south late Monday afternoon.
It happened shortly after the Coulson Aviation-owned aircraft had conducted a second retardant drop on an out-of-control bushfire near Hopetoun.
Both pilots were able to walk away with minor injuries despite the plane becoming engulfed in flames and smoke upon impact.
The men, believed to be Canadian nationals, were released from hospital on Tuesday.
"It's nothing short of miraculous that they were able to walk away from that plane," Emergency Services Minister Stephen Dawson told reporters.
"We're very grateful that they are healthy and well."
The Australian Transport Safety Bureau is investigating what it says is the first serious accident involving a Boeing 737 in Australia.
A different Coulson-operated firebombing aircraft crashed in the NSW Snowy Mountains in January 2020, killing three people on board.
Chief Commissioner Angus Mitchell said it was too early to suggest any link between the two incidents or wider implications for the 737 airliner fleet.
"This is fairly common that air tankers are converted from other uses," he said.
"In terms of a large aircraft like this coming down, it's generally never one thing that goes wrong, it's quite often a succession of things."
The plane had taken off from Busselton-Margaret River Airport, about 500km away from where it crashed.
Opposition emergency services spokesman Martin Aldridge has called for a pause on the use of the large air tankers.
Mr Dawson said the government would take advice from the safety bureau but the aircraft were a vital part of the state's firefighting arsenal.
A replacement large air tanker from NSW is due to arrive in WA in coming days.
Coulson Aviation, whose owners are believed to be travelling to Perth from Canada, said it was grateful the pilots were safe.
"Our thoughts and our immediate concern is for those team members and their families," it said in a statement.
Investigators will interview both pilots and witnesses and recover the plane's flight data recorder once it is safe to do so.
Mr Mitchell said it was fortunate the aircraft appeared to have landed horizontally.
"A large aircraft going down is generally quite catastrophic ... these pilots, I'm sure, are very lucky to be alive," he said.
Authorities say the bushfire, which has burnt through 2000 hectares and remains a possible threat to lives and homes, was caused by lightning.
More than 120 firefighters are battling the blaze.
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