Skiing, like many other sports, carries the risk of injury. It's important you know what to do if someone gets injured on the slopes.
If a member of your party gets injured on the slopes, plant a pair of crossed skis above the accident site to warn other skiers and mark the location. Then call the ski patrol. At least one person should remain with the injured skier at all times.
Make sure the casualty is as warm as possible and take off their skis (but not boots). If there's any possibility of a neck or spine injury, don't move them.
Staunch any bleeding by applying direct pressure and elevating the limb, if possible.
Lie an unconscious skier on their side in the recovery position, ensuring their mouth is empty of snow and vomit. If they're not breathing, you'll need to resuscitate them.
A ski pole makes a handy interim splint for leg, knee and ankle injuries. For arm injuries, use a scarf or jumper to immobilise the limb.