I was using the measurements that were in this link which is dead now. https://www.flugplatzsiedlung.de/Pent_gate.pdf Here's a way to do it. Go to the sixth picture from the top in this link. https://web.archive.org/web/20111205224534/http://0911.voila.net:80/index4.htm The length of the side of the Pentagon can be used as a reference point. A small error in measurements can turn into a big difference so it has to be super precise. I don't claim to be able to to that but here's what I got. When I put my metric measuring stick on the screen, I got a length of .0016 meters for the length of the space behind the gate-lifting mechanism and and .0114 meters for the length of the side of the Pentagon. The length of the side of the Pentagon is 281 meters. .0016 times 281 divided by .0114 = 39.43 meters which is 96.55 feet according to this... https://www.rapidtables.com/convert/length/meter-to-feet.html According to this... https://en.wikipedia.org/wiki/Boeing_757#Specifications ...a 757 is 155 feet long. I'm not saying I didn't make any mistakes. You people try it and see what you come up with.