What traits do they possess?
A leader is inspiring and motivating, calm and collected, responsible for their actions and a good listener.
How do you think a good leader manages crisis under stressful situations?
I think he does not haste to make a decision and instead calms down to think through the current situation and the best way while keeping his team under control to not make any hasty actions. He would then try to trace the problem back to its root and try to solve it and bring the team back together with the help of everyone in the group.