I’m convinced it was an interdimensional portal
Oooh, I know this one! The FAA (Federal Aviation Administration - they make the rules for flying here in the US) has designated “roads” in the sky to keep all the commercial jets from running into each other. When you’re headed the same direction at the same speed, you don’t get in each other’s way. If you’re heading east you fly at one elevation, and west-bound planes fly at a different height. There are lots of rules to keep mid-air crashes to a minimum.
However, if you’re running late, or weather in one spot is bad, you can call up Air Traffic Control and ask for a new route! And they will look at their little radar screens and maps of all the airplanes in the area, and tell you what shortcut you can take.
I am a little bit overcome by this. We made actual imaginary tunnels in the sky so our giant metal birds can fly through the open air in the most organized, polite way possible. We check in over our designated long distance thought projection machine channel that anyone can listen in on but we all promise not to interrupt to get permission to swap imaginary sky tunnels. We come up with the weirdest impossible shit and immediately give it boundaries! Humans are ridiculous. I mean yes these are good rules and many many people would die if we didnt have them, a+ on these rules, but if you take a step back wanting to sunder every natural limitation we can find and then going ahead and building our own so nothing gets too messy is a fucking hilarious art for a species to compulsively pursue.