The final flight of the doomed Rossair plane that crashed in the South Australian Riverland, killing three experienced aviators, lasted no more than 90 seconds, investigators have revealed.
The Cessna Conquest appears to have fallen steeply, given the concentrated crash site in scrub less than three kilometres from the Renmark Airport, the Australian Transport Safety Bureau said.
Five ATSB investigators have taken charge of the scene and chief commissioner Greg Hood says their inquiry will be complex.
"In my experience, it's an unusual accident and it's not something that you can put your finger on and say that's likely to be the cause straight away," he told reporters on Thursday.
"We don't see these types of accidents very often in Australia."
The Rossair plane crashed on Tuesday afternoon, killing the company's chief pilot Martin Scott, 48, fellow pilot Paul Daw, 65 and Civil Aviation Safety Authority inspector Stephen Guerin, 56.
Mr Hood said the plane had only been in the air for about 60 to 90 seconds before it plunged to the ground.
The ATSB would not speculate on a possible cause at this stage as it began to examine the wreckage, radar and other data and also examined details of any incidents involving the same Cessna aircraft around the world.
However, the scenarios likely to be considered include mechanical or fuel-related issues, a possible bird strike and the impact of any training exercises being conducted, including a simulated engine failure.
Investigators would also check on the maintenance and flying record of the Rossair plane and could decide to reconstruct parts or all of the aircraft.
Mr Hood said because of its size the Cessna was not required to have flight data or cockpit voice recorders but that would not necessarily hinder any discovery of the cause of the crash.
He said the fact that there was no post-impact fire would also help his team and stressed that the aim of the ATSB investigation was not to lay blame. but to prevent a similar accident happening again.
"It does take some time and methodical analysis to truly understand what happened in a complex accident such as this."
The ATSB plans to issue a preliminary report within 30 days and a final report within 12 months.
Rossair has grounded its operations and said it would co-operate fully with the investigation.
The company will take advice from the CASA on when it can resume operations.
