Passengers Joey King and his fiancee Rahula Hohua, skydiving instructors Glenn Norman and Juraj Glesk, and pilot Andrew Aitken died when the Cessna 206 crashed and burst into flames shortly after taking off from the Caboolture Airfield, north of Brisbane.

Investigators have not determined what caused the plane with no engine problems to crash on a clear day in March 2014.

It crashed on its left wing after rolling left suddenly at around 200 feet in the air.

But a mechanism to prevent the pilot's seat sliding backwards was missing, Australian Transport Safety Bureau investigator Eric Blankenstein has told the inquest in Brisbane on Monday.

Unwanted seat movement may have led to Mr Aitken losing access to the controls, while the low flying height meant he was unable to regain control.

A secondary device to stop unwanted movement was also unfitted.

A disused co-pilot's controller was also unsecured and could have contributed, according to Mr Blankenstein.

The inquest before coroner Terry Ryan is also set to explore whether additional industry regulations need to be implemented.

Australian Associated Press