Well, one of my points is that you're assuming the two colliding airplanes are heading directly at each other. If they're not, but rather beside each other slowly closing, there's plenty of time for a pilot to evade when they are eighty feet apart.
Aside from that, the point is that on one front end, the two aircraft collided, but on the other front end, they passed with eighty feet to spare. The second pilot, the one who sees eighty feet of seperation, doesn't need to maneuver.
You seem to be claiming two erroneous things. One is that whenever one pilot collides on his end, the other one would have to collide on his end also because there is no time to maneuver with only eighty feet. As I pointed out, just because there are eighty feet between them doesn't mean that they are going to collide. On the second pilot's front end, they're probably not going to collide at all.
The other false notion you have is that if two airplanes are on a collision course and there is eighty feet between them, they have to be facing each other and therefore only giving them a fraction of a second of time. This is also quite wrong; what if one pilot is eighty feet behind the other and closing? If he continues on his course, they will collide, but it will take a lot longer than a fraction of a second.
I'll try one final time to explain the situation. Two pilots can be on a collision course. Let's use my previous example of one pilot behind the other, travelling faster. On his front end, there are one hundred and eighty feet between the two. On the end of the pilot ahead of the first pilot, there is only one hundred feet's distance. If the first pilot (the one behind) is travelling at 300 M.P.H. and the second at 290 M.P.H., then that gives them about seven seconds before they reach the point at which the first pilot's front end will show the ships being eighty feet apart and the second pilot's will show the ships colliding.
P.S. Your mathematics are also wrong, I believe. According to my calculations, 600 M.P.H. should be 880 feet per second, not 172 feet per second. The calculation I used was 600 M.P.H. times 5280 feet per mile divided by 60 minutes per hour divided by 60 seconds per minute. If this is wrong, then demonstrate why.