Search crews earlier today found the wreckage of the Cessna 206, which went missing yesterday on a flight from NSW to Brisbane.

A NRMA CareFlight helicopter landed at the crash site, with a doctor confirming all three occupants were dead.

A search helicopter sighted the wreckage around noon (AEST) today at Hanging Rock, about 55km north-east of Scone, in the upper Hunter Valley.

The plane, which left Sydney's Bankstown Airport yesterday morning, had stopped to refuel at Scone before taking off again.

NRMA CareFlight had landed in a clearing about 100 metres from the crash site, which was located at the top of a mountain in rugged terrain, a statement said.

"The helicopter landed at the scene where the NRMA CareFlight doctor confirmed all three occupants of the plane had been killed on impact," it said.

"The NRMA CareFlight doctor said wreckage of the Cessna 206 was spread over a wide area, about 55km north-east of Scone (on) a peak at an elevation of about 1,500 metres."

Concerned relatives notified authorities yesterday after the aircraft failed to arrive at Brisbane's Archerfield Airport.

Those aboard had not lodged a flight plan with authorities.

Several light aircraft and four or five helicopters were involved in the search, along with a Dornier twin-engined turboprop plane with inbuilt thermal imaging equipment designed for long-range search and rescue.

On board the single-engine plane were a male pilot, with a female passenger and her young son, NSW Police said in a statement.

"The aircraft, being piloted by a 39-year-old Brisbane man, left Bankstown airport about 8am (AEST) yesterday with two passengers, a 38-year-old Brisbane woman and her seven-year-old son," police said.

Poor weather and rugged terrain is hampering efforts to retrieve the crash victims' bodies.

"Due to deteriorating weather the retrieval of the bodies is expected to take place in the next couple of days." police said.