[reacweb]

This gives a lot of importance to small airports in small islands. Big international airports are surrounded by other smaller airports. They are associated with a tiny surface. I can not see how this representation may be of any use for airports.

[acjohnson55]

It doesn't seem to me that it's designed to be "useful" as much as just interesting.

[schreiaj]

Ability to divert in an emergency?

[perilunar]

Absolutely. It's a map of closest airport for any location on earth.

You could do different versions of this for different classes of plane (e.g. select a minimum runway length).

[mikeash]

This has a big influence on which routes a plane can fly. You can’t be more than a certain distance from a usable airport at any time during the flight to mitigate the risk of engine failure resulting in an off-airport landing/crash. See: https://en.m.wikipedia.org/wiki/ETOPS

[isostatic]

And diversion airports of course vary with things like weather

[jypepin]

I guess that would be useful in a case where you'd want a representation with an importance that is reversely proportional to the airport importance.