It is believed the 77-year-old man from Sydney, who was travelling along Port Stephens drive about 8.10am, suffered a suspected heart attack before losing control of the vehicle and striking the pole.

Port Stephens police investigators are exploring the possibility that health issues were the cause of the single vehicle crash.

The man was flown by Westpac Rescue Helicopter to John Hunter Hospital where he was reported as being in a stable condition on Tuesday.

A telling 10 minute period before emergency services arrived may be the reason the man is still alive today.

Three passers-by, all unknown to one another, kept the man's heart beating while a fourth person logged a call to paramedics who arrived shortly after.

Michael Raftery from Birubi Surf Lifesaving Club was second on the scene.

The experienced, and first-aid-trained lifesaver said his and the work of three other people in keeping his heart beating was a remarkable team effort.

"The big thing for me was that it [the operation] worked really well," Mr Raftery said.

He said he noticed trouble ahead before pulling over and taking part in the lifesaving exercise.

"I could see that someone was going to be injured, it was a fair impact," he said.

A thorough search of the bus by one of the by passers found no other passengers.

One of four that initiated CPR, Mr Raftery wanted the others to make themselves known so that he could thank them in their efforts in saving the elderly man.