A preliminary report into the cause of the crash is due within weeks, while a full report will take much longer to prepare.

However, ATSB transport safety director Stuart Macleod said immediate action would be taken if there was "any critical safety issue identified during any aspect of this investigation".

Two people, a man and a woman, died in the crash about 7.15pm on Wednesday.

Their plane had taken off from Bankstown Airport on Wednesday with a flying teacher and student pilot on board.

It landed and took off safely from Orange Regional Airport before crashing at a remote airstrip on a private property in Carcoar.

Officers attached to Chifley Police District guarded the site overnight on Wednesday until police and ATSB investigators arrived on Thursday morning.

Once on-site, ATSB investigators conducted a full examination of the wreckage and carefully mapped the site, including taking aerial footage from a drone.

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"A team of four investigators has departed from the Canberra office this morning with expertise including aircraft operations, maintenance, engineering and human performance," Mr Macleod said.

"The team is expected to be on-site at the accident for the next several days examining the aircraft and the accident site itself.

"That will include looking for recorded information that there may have been on board for future analysis back here in the laboratory.

"It's also going to consider the airstrip that the aircraft was reportedly operating from immediately prior to the accident, in terms of its suitability. We'll also be looking at aspects such as the weather and the qualifications of the two involved pilots on board the aircraft."

Mr Macleod urged any witnesses who may have "observed any aspect of this flight" to contact investigators at atsb.gov.au or by phoning the ATSB witness hotline on 1800 992 986.