The rescue of climbers above the cloud requires the helicopter to get the mountain rescue team and high as safely possible then they go to work doing what they do!! The helicopter then returns once the casualties are below the cloud to take them to safety. This particular rescue proved difficult for the helicopter crew due to the snow making depth perception difficult and determining where the mountain ended and sky began. Added to that, when the helicopter approached the hill, downdraft causes snow to envelop the aircraft making it even more difficult to see the hill.
The climbers had inadvertently spent the night on tower ridge and suffering for exposure/hypothermia required help in getting down from the hill.