Not a topic I know anything about but it reminded me of dramatic videos of pilots with near misses with ultralights. This is obviously much slower than two commercial jets going opposite directions. But notice how quickly the ultralight appears out of nowhere in this video Show it full screen and look carefully, it's visible as a tiny dot comes out of the distance, first visible at about 15 seconds in, but only once you know to look for it (or maybe if you have a pilot's eye and are looking at it??), and has passed the plane by 22 seconds, so all over within about 7 seconds.