A BASE jumper who plunged to his death from Australia's tallest structure may have been wearing a helmet camera, which could hold clues to what happened.

Fairfax Media believes Ash Cosgriff, a 23-year-old skydiver and BASE jumper, plummeted to the ground near the Omega tower, a 432-metre navigation antenna and transmitter, at Giffard, about 200 kilometres east of Melbourne, just before 2.30pm on Saturday.

Police believe a helmet was removed from Mr Cosgriff's body before emergency services arrived. A mount for a camera was attached to the helmet, but no camera was found.

Mr Cosgriff, a member of the Newcastle Sports Parachute Club, was a skydiver who also did BASE jumping on the side.

BASE is an acronym for building, antenna, span (bridge) and earth (cliffs) - the four places from which jumpers launch.

Mr Cosgriff also belonged to a subgroup called Skydive Elderslie, which included local residents from the Elderslie region, near Sydney.

The drop zone safety officer at the Newcastle Sports Parachute Club, Michael McGrath, said Mr Cosgriff held a D-licence in skydiving and had made more than 200 skydives.

Mr McGrath said it was important to differentiate between skydiving - an activity that is regulated by the Civil Aviation Safety Authority - and BASE jumping, an illegal and unregulated parachute jump from a fixed point, usually from a tall building or promontory rather than an aircraft.

In skydiving, a person carries a reserve parachute, Mr McGrath said. In the case of BASE jumping, a person has the use of only one parachute, which is usually opened very close to the ground.

''From what we hear, Ash deployed his parachute marginally too late and, before it had time to completely open, he impacted the ground,'' Mr McGrath said.

He said Mr Cosgriff's tragic fall would not deter other BASE jumpers, because ''BASE jumping is a high-risk sport and people who do it know the risk''.

Police said it was most likely a parachute malfunction that caused Mr Cosgriff's death, and that they were searching for another man they believed was with Mr Cosgriff when he died.

''We are concerned someone removed his helmet from the body, which had a mount for the camera,'' Detective Sergeant Ian Marr said. ''The person who left the scene is most likely the friend of the person who has been killed. I suspect he may have been spooked and run off. But he really needs to come and speak to us.''

With AAP