How did Captain winter fall in the book Banner in the Sky?

In "Banner in the Sky" by James Ramsey Ullman, Captain Winter falls while attempting to rescue Rudi Matt, the protagonist, during a dangerous climb. As Rudi reaches for a hold, Captain Winter slips due to the treacherous conditions and loses his footing. His fall serves as a pivotal moment in the story, highlighting the perils of mountaineering and the bond formed between the characters. Ultimately, Winter’s sacrifice emphasizes themes of bravery and the spirit of adventure.