Yet another Hacker News

Show HN: Live map of U.S. flights during tonight's FAA nationwide ground stop

42 points gvsi 3 hours ago 8 comments

cobychapple 1 hour ago | parent

Fun irony (beyond being Friday the 13th): FAA lost radar and frequencies between centers but ADS-B is broadcast by the planes themselves, so a couple hundred hobbyist receivers probably kept the full picture the whole time.

monkeymeister 1 hour ago | parent

Wow, impressive TTM. Barely enough time for the domain to resolve!

gruez 1 hour ago | parent

>Barely enough time for the domain to resolve!

contrary to popular belief, DNS doesn't actually need 24 hours (or whatever) to "propagate". It only needs enough time for caches to expire, if they exist. For non-existent domains this shouldn't be an issue.

gnabgib 1 hour ago | parent

DNS controls the length of time an answer is valid (with time-to-live/TTL), some (poorly configured, but for a historical good reason) caching servers ignore the TTL and keep the record much longer (~24 hours).

A non-existent (not yet resolvable) domain, will get an NXDOMAIN response which also gets cached via a TTL setting (which again might be ignored by caching servers).

All that caching - while the current response is still "valid" because the TTL hasn't expired - is what people call "propagation".

halamadrid 1 hour ago | parent

Really fast work! I didn't know all of this data was publicly available.

gvsi 55 minutes ago | parent

I remember seeing a similar cool GIF for 9/11 flights, and thought it'd be cool to see if for today's ground stop too, and had Claude Code generate the website in ~30 mins.

Liked it so much and thought I'd clean it up a bit, deploy, and share :) Enjoy!

thirtygeo 22 minutes ago | parent

Everyone I shared this with while stuck in transit today loved it. Thanks for inspiring some good vibes in Montreal!