How does training go with kens back up jack in the Apollo 13 movie?

In the movie "Apollo 13," training with Ken Mattingly, who was originally part of the mission but was replaced due to illness, plays a crucial role in the team's preparation for the crisis. Mattingly's deep understanding of the spacecraft systems and his ability to think critically under pressure are highlighted as he provides guidance and support to the crew during their challenging situation. The training emphasizes teamwork and the importance of knowledge transfer, showcasing how Mattingly's insights help the astronauts navigate the life-threatening challenges they face. Ultimately, his contributions demonstrate the significance of thorough preparation and adaptability in space missions.