Keep calm in the face of stress and keep in mind that the other people who are in the same situation you find yourself in are probably just overreacting anyway. In a chaotic environment, you are called on to be the voice of reason. Count to ten, take a deep breath and go ahead with the proper procedure. You`ve had plenty of training for this kind of thing, so you should be able to operate on automatic pilot if need be. Things might be stressful for a minute or two, but it shouldn`t take you long to get the situation completely under control.