I feel absolutely a-okay with a potential anarchist future where the infrastructure needed to build an airport is non-existant. Really, if you think about it, airports are the easy bit - a large enough level field and (maybe) a building or two. If we can't muster enough organization to pull that together, then there is no way we will maintain fleets of airplanes, continue to extract the fossil fuels they run on, etc.
Snarkiness aside, why couldn't anarchists build an airport and maintain serviceable airplanes? What makes it so that capitalism does so? Markets? If so, that is invented and/or monetized needs. If there was a need and desire there is no reason some anarchists might not choose to build and maintain an airport, though I will admit that I find a hard time reconciling the building of airports and the maintaining of air travel with an anarchy I want to be involved with, and I bet things would get uncomfortable when the airport anarchists collectively decided that they needed to expand their airport into the farmlands of the next collective over who perhaps want to keep growing kale and fava beans for the masses (never mind any individualists and egoists - they are just loose cannons, and I am sure that collective immanent domain trumps their desire to live where the new landing strip should go).
What will happen when, due to expanded flights on Libertarian Air, the LibAirCollective realizes they need more fuel and that that fuel exists in a place where the residents don't have a mutual aid and trade agreement? Maybe those residents don't like the potential risks to their water quality that comes with resource extraction and the infrastructure (trains? pipelines? freeways? another airport?) required to transport said resources....
I diverge from the actual intent of your question, but I do so because I think your framing (or maybe more accurately that of the person you were talking to who is focused on macroeconomics) deserves to be challenged on the level of assuming that an anarchist world would look anything like this one, or that we would be striving to maintain things like air travel, which are in and of themselves products of capitalism.
This anarchist suspects that it would be ultimately more desirable to abandon many technologies taken for granted in modern industrial civilization (airborne travel is in that list). Then again, I am not so interested in convincing folks who are not anarchists of the righteousness of my perspective, especially if I would need to water down my beliefs to meet their cynicism about things like collectives, or terms I feel emnity towards, such as socialism. Forget it. I am not trying to win converts.