>>936564694even the most basic commercial/military planes move at 500mph (800kmh)
the human eye can, at best, see 3 miles (5km) ahead of him
that means if you see an object moving at that speed, you will have less than 20 seconds between you see the object to move away from his trayectory
now do the math if both planes are in the same line facing each other
thats why air traffic exists