My favorite is the hopi reservation, which does not observe DST and exists entirely inside of the Navajo reservation, which does observe it, and which exists entirely within Arizona, which again does not observe DST, and exists entirely within the United States which does observe DST in the general case.
I'm guessing that the airport was this one maybe? ttps://en.wikipedia.org/wiki/Window_Rock_Airport
Also IIRC (cum grano salis) the federal buildings in the Hopi reservation do observe DST and the state buildings in the Navajo reservation don't. But don't quote me on any of those actually existing.
A fun fact circa 2012 was I was writing a PHP server that needed to talk to a Windows server to schedule things. Windows server used Microsoft's own timezone system, not IANA or anything like that. I went looking for an implementation of IANA <-> MS conversion. I ended up finding all these forum posts by Windows Phone (RIP) users in Arizona who had the wrong time on their phones. So it was nice to know that 1) there was no fixing it and 2) they eat their own dogfood.
