How can you tell if you’re on a collision course with another airplane? Your biggest clue will be that there will be no relative motion between your airplane and the other aircraft. If you can maneuver in such a way to make the other aircraft appear as though it’s moving relative to your location in the sky, you have altered course enough to avoid running into each other.
That sounds pretty straightforward, but remember: The human eye is more sensitive to movement in peripheral vision, and as a result an object that doesn’t appear to be moving is harder to detect. That’s why you must actively scan the sky, normally in short intervals by focusing on about 10 degrees of the sky at a time.
