You'd be surprised. Years back, I saw what looked to be a near midair collision, including a smoke trail from one of the involved aircraft, and watched for a wh

You'd be surprised. Years back, I saw what looked to be a near midair collision, including a smoke trail from one of the involved aircraft, and watched for a while from the front right seat of the Jeep my boss was driving us to a job site in. Presence of mind isn't really an issue. You're more just trying to understand and follow what you're seeing. Today, of course, I'd be watching through my 500mm lens and taking pictures all the while. This was long before I got back into photography, though, and long before you could get a 500mm tele that didn't cost as much as a car. Even so, it was interesting, not frightening - remember that the sky is a long way away, and so are most things that happen there, weather notwithstanding. Never did find out what actually happened.