A former bus driver for Ruapehu Alpine Lifts says shuttles and drivers are under too much stress and Saturday's fatal crash was an accident waiting to happen.

Photo: Supplied.

Allan Henderson, who was one of the company's first contract drivers, drove the Whakapapa side of the mountain but back then the buses transported staff, not skiers. These days he works as a driver for National Park Backpackers.

The sheer numbers of skiers needing transport up and down the mountain was putting too much pressure on bus and shuttle services, he said.

Mr Henderson wanted bigger carparks and shuttles banned from the mountain altogether.

On Saturday, 11-year-old Hannah Francis was killed in a bus crash on the mountain which left 18 other skiers injured. Ruapehu Alpine Lifts runs the main service up and down the mountain.

"My opinion, and I've said right from the beginning, it was an accident waiting to happen," Mr Henderson said.

"You get those people up, you've gotta work your buses hard to get them up there, and when you come down in the afternoon all everyone wants to do is get down again and it's all downhill ... it's hard on buses, it's hard on drivers, they should never have started the shuttle service up."

Yesterday Ruapehu Alpine Lifts announced it would voluntarily suspend its bus fleet after an urgent audit carried out by the New Zealand Transport Agency.

The chief executive of Ruapehu Alpine Lifts, Ross Copland, has refused repeated requests for an interview with Checkpoint.

The Ministry of Business Innovation and Employment said, despite the investigation, it will proceed with plans to loan Ruapehu Alpine Lifts $10 million towards the construction of a gondola project across the Whakapapa ski field.