Eighteen-year-old Anthony Christensen from Birkdale, QLD, was snowboarding away from the main area at Guthega when he moved out onto the Guthega Road and was hit by the NPWS truck, police said.

He suffered serious head injuries and fractures to his skull, jaw, cheek, pelvis, collarbone and ribs and had to be placed in an induced coma.

But his father, Naval Chief Petty Officer, Rick Christensen, said: "If he had been wearing suitable headgear the injuries wouldn't have been as serious. You're not bullet proof. Your head has to be your first thought because if you break that, everything else fails."

Anthony Christensen's family was contacted by Cooma Hospital and within an hour was on the road to Canberra to be by his side.

Due to the weather conditions at the time, the Snowy Hydro SouthCare helicopter was unable to fly into the area and Anthony had to be transported by road to Cooma Hospital and then airlifted to the Canberra Hospital.

The circumstances of the accident had been very unusual, Mr Christensen said.

"We understand that he overshot the run where it comes out onto the road. Sergeant Moodie (from Jindabyne Police Station) told us that it was virtually impossible to reproduce the situation"

The run was understood to have been closed.

Mr Christensen said: "My son is a good boy and it's his strength and fitness that have got him through this."

Anthony is now in a stable condition although it is not certain how long he will need to stay in hospital. It is also unclear whether Anthony suffered any brain damage.

"He has serious recall issues over the short-term but things are looking very promising," Mr Christensen said.