This week has been a huge one for rime icing conditions on Ruapehu. On Sunday night we had some of the fastest build-up of rime ice ever seen overnight. It's meant a lot of hard physical work for our de-icing crews over the week.

Snow TV managed to get up here to capture some of the behind-the-scenes action. Check it out here.

And while we're talking about de-icing, here's a few answers to some frequently asked questions we get about it:

What is riming?

When cold moist air hits the steel of our lift components the moisture sticks hard to them as ice and then, if the same conditions persist, it builds on itself sometimes at a rate of 5-10cm an hour!

Why don't you guys just turn on the lifts like at other ski areas?

Ruapehu gets some of the harshest rime icing conditions in the world. The weight of it has even been known to bring down lift towers in the earlier days at Whakapapa! This is because Ruapehu is an exposed mountain, not protected by a mountain range and it gets most of its winter weather from the moist North-West. When an ice storm hits we need to get the ice off all the moving parts of the lift before we start up in the morning.

Why don't you just go up earlier to de-ice?

Snowmaking and night crews do work on 'cracking' and running lifts during the night to help make the de-icing crew's job easier in the morning. The trained de-icing crews get here at 6:30am and start work on the lifts as soon as there is enough light for it to be safe. In the dark their job, which entails climbing ice-laden lift towers, would be too unsafe.

Why don't you get more staff de-icing?

For safety reasons each member of our de-icing crew has to be fully trained on a 1/2 day theory course followed by three days buddying up with an experienced crew member. We already have 80% of all our lift crew plus members of our Trail Safety and Terrain Park crews trained and we're continually working on getting even more. Our biggest priority on any morning is getting lifts open for you so every available trained person gets up there and works at it one lift at a time. As facilities open the pool of available people diminishes as they're required to do other jobs like operate the lifts that are running.

Why do you de-ice the lower mountain lifts first?

The order that we de-ice lifts is pretty obvious really. We start at the bottom and work our way up. It makes sense because we need the lower mountain lifts to operate first to provide access to the upper mountain lifts. Our grooming and safety crews work in the same order so it all comes together to open the most terrain possible as early as possible every morning.

Mt Ruapehu Newsletter 24 July 2009