What are all the possible reasons to do this?

Has this ever happened?

A credible threat from Iran? More likely a technical issue.

Happened in 2023 https://www.faa.gov/newsroom/faa-notam-statement

It happened on 9/11, didn’t it?

yes, 9/11

[delayed]

Jan 2023 was the most recent nationwide one.

https://www.cnbc.com/2023/01/11/faa-orders-airlines-to-pause...

https://en.wikipedia.org/wiki/2023_FAA_system_outage

previous time it happened right before chinese baloon made the news

it may be something similar - remove all random, but controllable sources of radar return for military to start scanning

"Frequency outage", I think that translates to radio communications not working, until "22 Zulu" aka 22:00 UTC, 5 PM ET.

How does one prevent transmission on a frequency in an area the size of the continental US?

It's radio. Either you jam it or it works. That's the selling point.

It's not the transmitting per-se. The network that gives controllers access to the en route radio system isn't letting them connect to the radios.

I guess some of their floppy drives must have given out.

Pilot forum discussion - https://www.pprune.org/rumours-news/674910-us-wide-ground-st...

Microsoft outage related??

good question

I can easily imagine a batch job on a mainframe that sends every hour some important data by mail and that some logic apps checks that mailbox to propagate the data but now that mails have been delayed +12hours it's going haywire

Some more discussion: https://news.ycombinator.com/item?id=50489641

Please for the love of god ban this bot

+1 ban it and with it the 30k+ Karma it has

Why? I came into this thread just to make sure someone posted that link. I hate when the discussion gets fragmented across several different posts.

Dang does that too. I guess we are going to have to ban him as well.

Looks lifted now. https://www.fly.faa.gov/adv/adv_otherdis?adv_date=11132026&a... https://www.fly.faa.gov/adv/adv_otherdis?adv_date=11132026&a...

If you refresh a few times it'll show the advisories.