ATCSCC Advisory
ATCSCC 111 DCC 11/13/2026 NATIONAL GROUND STOP
EVENT TIME: 13/2053 - 14/0400
DUE TO EXTRAORDINARY CIRCUMSTANCES AND FOR REASONS OF SAFETY.
ATTENTION ALL AIRCRAFT OPERATORS, BY ORDER OF THE FEDERAL AVIATION
COMMAND CENTER ALL AIRPORTS ARE GROUND STOPPED. ALL DEPARTING
TRAFFIC SHOULD REMAIN GROUND STOPPED UNTIL FURTHER NOTICE. INBOUND
INTERNATIONAL FLIGHTS WILL BE MANAGED ON A CASE BY CASE BASIS.Why
reply13/2053
?
It's a format called "Date-Time Group" (DTG). Used in military, I think it dates back to teletypes, and is better to say over radio than modern ISO formats.
replyYou'd say "Valid from the thirteenth at two zero five three zulu" over radio.
The TLDR is that punchcard operators found the DTG date format convenient. Punchcard sorting is easiest when the consecutive bits encode the sort key, and the DTG format is easy to split into different sets of bit ranges corresponding to common business logic.
replyAirplane software is some of the oldest on the planet, pre-dating anything that would be considered a best practice. When you see something weird in the space, assume it is because someone in the 1960s thought using more than two characters world be a profligate waste of space.
replyUnrolling these decisions is a monumental task given the decades of hardware already deployed in the field that will only be upgraded when the current unit fails.
> When you see something weird in the space, assume it is because someone in the 1960s thought using more than two characters world be a profligate waste of space.
replyAnd with 1960s technology, this might just have been a very reasonable decision.
Totally. Just some of those decisions put awkward constraints when the hardware is now a million times more capable.
replyMy guess at parsing: in effect from 8:53pm UTC on the 13th to 4am UTC on the 14th.
replyFriday the 13th at 08:53 PM UTC
replyUTC
replyHoly french.
replyFrom Reddit:
replyOh nice, very helpful. The sibling thread mentions that this problem is specific to "ARTCCs", which are not the towers at airports but rather central hubs:
reply Between the sectors administered by [smaller towers] are 20 contiguous areas of US airspace above 18,000 feet, each managed by an Air Route Traffic Control Center (ARTCC)...
A flight is handed off from one Center to another until it descends near its destination, when control is transferred to the TRACON serving the destination, and ultimately to the tower controller serving the airport.
https://en.wikipedia.org/wiki/Area_control_center
EDIT: someone below posted this, seems relevant -- the 'Radar multiplexer pipeline' that's on a "fast track" and an "aggressive track": https://www.sunhillo.com/wp-content/uploads/2025/04/SUN3125-... TL;DR: upgrading radio systems from old analog tech to new digital tech, I think?
I'd be shocked if someone greenlighted an atc upgrade procedure which involves closing all US airspace to do the switchover.
replyThat’s obviously not what’s happening. But if this upgrade is really implicated, the real question would be where the line of accepted residual risk for an outage like this was drawn.
replySorry I was unclear; the guess is that it caused an issue, not that they did this on purpose with no warning.
replyWell sure, but I wouldn't be shocked at all if someone greenlit a plan that wasn't supposed to involve closing the airspace, but which failed and which had an insufficiently thought out rollback plan.
replyFor anyone who doesn’t want to click through, there are problems with “frequencies”. Something must be jamming up the airways… but nationwide??
replyProbably a telecom issue. Most radio transmitters are operated over phone or Internet from a remote station.
replyTeams phone down?
replyAre these systems dependent on landlines?
replyVZW and AT&T are moving full tilt in shutting down landline central offices.
Literally the gay dude from Airplane pulling the plug from the socket may have happened here.
Na most are VoIP nowadays.
replyLooks fake. Outtages (sic)?
reply
Seems “not great” that the notice isn’t even showing…
replyIt disappeared briefly, but is back now.
replySame here, I get it only on some refreshes, otherwise it shows "no advisories". I hope that's not the main path these things are disseminated normally.
replyThis thing is probably getting 10,000+% normal traffic, database is timing out on some queries, and it represents no answer as no notice.
replyThat would be a pretty concerning way of handling database failures, but I suspect you might be right.
replyPower is off? Let the dinosaurs out.
reply