In neither of those situations did I feel any kind of fear. Instead, I felt detached, like an outside observer, rationally seeing the options and taking the appropriate actions.
Yet when faced with situations that are much less deadly, such as when a student confronts me physically, I have difficultly acting rationally at all. My throat clenches up, my chest tightens, a vein on my left temple begins to throb, and all I can think about is how angry and scared I am. This doesn't mean that I don't act, or even speak, but that my actions and words come out without any thought behind them, often worsening a situation unless I can somehow bring my fear response under control.
This is a reason why I don't think I could survive in politics. I see the pressure that politicians are put under and I know that some of my responses in those same situations would not have much, if any, thought behind them. This is especially true for any argument that attacks my core values or beliefs.
Usually, it isn't for a number of minutes, if not hours, before my mind actually activates and processes what my best responses to these situations would be. By then, however, it is too late. Sometimes, if I'm lucky, my thoughtless responses were good enough for the situation. Especially if it's a situation I've rehearsed in my mind, I can often come out fine without escalating the problem.
Unfortunately, interactions with people have more variables than interactions with vehicles. There are more possibilities than I can possibly contemplate, let alone rehearse, and they aren't limited to a road with reverse almost never being an option. Maybe that's why, even though the stakes aren't as high, the tension is.