Pilot dies in Qld light plane crash

A pilot has died in an ultralight plane crash off North Stradbroke Island but it's unclear what caused the plane to plunge into the ocean.

The 60-year-old man was the only person on board the plane which took off from the Straddie Aero Club around 10am (AEST) Saturday and was seen hitting the water about an hour later.

A distress beacon was detected at 11.20am, an Australian Maritime Safety Authority (AMSA) spokeswoman said.

The wreckage was spotted soon after, with television crews tweeting pictures of the plane.

Authorities recovered wreckage of the aircraft, which was mostly intact, and the man's body on Saturday afternoon.

Acting Superintendent Steve Dabinet said police were speaking with three witnesses as they piece together what caused the crash.

Acting Supt Dabinet said one witness saw the plane hit the water about 100m offshore, some 7km south of Point Lookout.

"As a result of that a search was conducted ... which involved 12 marine vessels and two aircraft," he said.

It was initially unclear how many people were on the aircraft, with some reports there could have been as many as six on board.

Police were still attempting to contact the man's next of kin late Saturday afternoon.

The AMSA will refer the incident to the Australian Transport Safety Bureau and Recreational Aviation Australia.

An aviation expert from Melbourne will arrive in Brisbane on Sunday to assist with the investigation and help prepare a report for the coroner.