Mount Rainier has a reduced ability to rescue people at high altitudes. Last year, a climbing ranger died during a rescue at 13,900 feet. Following that accident, the use of CH-47 Chinhook helicopters for hoist operation was suspended. That helicopter can operate at up 15,000 feet and lift victims into the helicopter.
Without that resource, rescues at high altitudes may be longer and more dangerous.
The park is working on a alternative helicopter rescue method, but it won’t be in action for a while.
What this means, in short, is that if you’re going to be climbing Mount Rainier, you need to know what you’re doing and be well prepared. If you get in trouble, you can’t count on a quick rescue.
The park has more information about it here.