A pilot and his passenger are in a critical condition after a helicopter carrying four people on a sunset tour crashed near Uluru in the Northern Territory.
The Professional Helicopter Services aircraft came down hard in scrubland shortly after take off about 6pm at a remote site 1.5km west of Yulara on Wednesday.
The pilot was flown to Royal Adelaide Hospital on Thursday morning in a critical condition with serious spinal and internal injuries.
His three passengers were all Australian.
One man who remains in a critical condition has been transferred to Adelaide on Thursday with serious spinal injuries.
The other two remain in Alice Springs hospital.
"There's a lady with a broken ankle and there's another man with minor injuries," a Central Australian Health Service spokeswoman said.
Another commercial helicopter was able to land and provide immediate help before The Royal Flying Doctor Service arrived near the crash site around 10.30pm.
Medical and police officers were hampered getting to the scene given the remote location.
"It has been a bit tricky for emergency services staff to get to," Northern Territory Police, Fire and Emergency Services spokeswoman told AAP.
A crime scene remains in place.
The Australian Transport Safety Bureau said in a statement it was investigating the crash involving a single-engine Robinson R44 helicopter.
"As part of its investigation, the ATSB will interview the pilot and witnesses and review available evidence," it said in a statement.