A party of three was descending the Tuckerman Ravine Trail on the summit cone of Mt. Washington when they lost the trail. Due to poor visibility, they wandered off trail to the east and began descending a steep snowfield. One of them caught her crampon, causing her to trip and start a sliding fall. One of the other people in the party chased her down and was able to assist her in stopping the sliding fall. The person who tripped had no experience self arresting. During the fall, the person twisted her ankle and her party was able to get her down to the Harvard Cabin in about 5 hours where they spent the night. The next day USFS Snow Rangers assessed, treated and transported the patient down to Pinkham Notch via snowcat.