Probably the most feared situation in aviation, besides perhaps an inflight fire, is a midair collision. One moment a pilot is enjoying the flight. He may be checking his chart or tuning a radio. Or maybe he is talking with a passenger or taking a drink of water. Suddenly there is a loud crash. The plane splinters, the wings crumple. The pilot, if he is still alive, has only a few moments to consider what happened as the airplane plummets to the ground.
Most pilots know the standard collision avoidance advice to progressively scan across the windshield. If they are honest, they will tell you that cockpit chores, the labor intensive modern glass cockpits, fatigue and just plain laziness keep them from accomplishing a consistent regular scan. So in reality, to a great extent we are relying on the”big sky theory.” When you look at the airspace available both horizontally and vertically, the chance of two aircraft being at exactly the same place at exactly the same time is almost nil.
