US national ground stop: ATC frequency outages

FlightAware counts about 2,650 cancellations on Saturday for flights within, into or out of the US. It also counts more than 8,860 on Friday. Both figures come via Euronews, published 0656Z. The article does not say when the Saturday figure was counted.

• The Saturday figure has risen sharply. ABC put it at "nearly 800" late Friday. More are likely as airlines finish rebuilding schedules around aircraft and crews that are out of position.
• Friday's count is larger than earlier figures. FlightAware's 8,860 is broader than NBC's earlier "more than 5,300", which counted differently and was taken at 0120Z.

No US airport is under a ground stop, and no new FAA advisories have been issued since O'Hare's stop was lifted at 0630Z.

The earliest radio failures HEXBIRD has found were all on frequencies served by one Chicago Center remote radio site. That site is the Jones RCAG (remote communications air/ground), near Jones, Michigan.

Coverage caveat: HEXBIRD has listened to a limited set of archived feeds, mainly a handful of Chicago Center sectors, Chicago approach, guard, and a few New York and Kansas City frequencies. Earlier or simultaneous failures on frequencies HEXBIRD has not heard, or that no public scanner archives, cannot be ruled out.

In the FAA's NASR database, Jones carries four VHF frequencies: 120.225, 125.975, 126.475 and 127.625. Three of the four appear in the first trouble reports; the fourth, 125.975, does not appear in the audio HEXBIRD has. The site's position comes from OpenStreetMap, where a "Jones RCAG" node is tagged to Chicago Center with the same frequency list.

The aircraft was not out of range. American 2774 was 24 NM from the site when the crew reported they could not hear 126.475. It passed within 1.6 NM of the site at 2011Z, at 32,800 ft, and was still working only on guard.

Was Chicago first? Of the facilities with problems that HEXBIRD knows of, Chicago is the earliest, by about 20 minutes:

Press reporting points the same way. CNN reported that the FAA told airlines the router problem was "believed to have started at Chicago Midway". The same coverage caveat applies: facilities HEXBIRD has not listened to could have had earlier problems.

Assessment: in the recordings HEXBIRD has reviewed, the evidence is consistent with this one site, or the telecom circuit linking it to Chicago Center, failing at about 2006Z, before the wider failure. It does not establish that Jones was the first failure anywhere in the system.

• How strong the evidence is. The two "can't hear" reports point most directly at the site. The "stuck mic" report is weaker evidence, because an aircraft with a jammed transmitter produces the same symptom.
• How it fits the network accounts. Remote radio sites reach their center over leased telecom lines, and the FAA's telecom network is run by L3Harris. That fits CBS's report of a failed network update, and Duffy's account of overloaded switches and routers.
• What it does not show. It does not show why Jones failed, whether other sites failed at the same time on frequencies HEXBIRD has not heard, or how the failure spread across Chicago Center in the following 15 minutes.

• O'Hare's ground stop was cancelled at 0630Z (Advisory 039, FAA database). No US airport is under a ground stop for the first time since 2010Z Friday, when O'Hare's stop began the night. That was 10 hours 20 minutes earlier.
• Traffic is back to normal for the hour. There were 1,221 aircraft above 1,000 ft over the lower 48 in the 0640Z window, against 1,249 at the same time Thursday, a gap of 2%. Overnight traffic is mostly cargo and long-haul, so this does not mean the airlines have recovered. Saturday's first departure bank, from about 1100Z, is the real test, with aircraft and crews out of position.

• The national ground stop lasted 4 hours 26 minutes, from 2053Z to 0119Z. Problems began at Chicago Center about 45 minutes earlier, at about 2006Z.
• Not yet back to normal. Overall the system is at about three-quarters of normal. In the hour to 0540Z:
  • Airline departures at 27 big airports were 72% of Thursday's figure.
  • Aircraft in the air over the lower 48 were 24% below Thursday at the same time.
• The recovery is uneven. East Coast hubs (Atlanta, Orlando, BWI, Charlotte) are running above normal as delayed flights leave late. San Diego, Phoenix, Dallas–Fort Worth and Newark are at 15–35%, and LAX, Seattle and San Francisco at about 50%.
• The restart has stopped and started. Since the lift the FAA has issued ground stops at 8 airports: O'Hare, Seattle, San Diego, Newark, Minneapolis, LAX, Dallas–Fort Worth and Atlanta. The reported reason is lack of space for parked aircraft, not new radio failures. All have been lifted except O'Hare, stopped again since 0417Z. Dallas–Fort Worth's was lifted at 0530Z.
• Every major US airline is affected. American, JetBlue, Air Canada and Southwest cancelled most of the rest of Friday evening. Airlines expect delays and cancellations into Saturday because aircraft and crews are out of position.
• International: Europe's suspension of US-bound departures ended at 0500Z. A Hong Kong NOTAM holds departures into US Pacific airspace until about 0800Z.
• Cause: officials blame overloaded network equipment ("old switches, old routers"). The FAA and L3Harris have not explained the failure on the record.

A more specific account of the cause. Homeland Security Secretary Mullin said new equipment was being installed alongside patches to the existing network, and the new technology overwhelmed the older system. He quoted Duffy: "the patchwork doesn't work." This is NBC's paraphrase from its live blog at about 0507Z; HEXBIRD has not found a full transcript.

It fits the earlier accounts:

• Duffy said switches and routers were "overloaded with data".
• CBS's sources described a failed update to the L3Harris-run network that crashed when it rebooted.

The FAA and L3Harris have still not described the failure on the record.

FAA advisories (database):

Dallas–Fort Worth (from 0341Z) and O'Hare (from 0417Z) remain stopped.

Traffic over the lower 48 is now following its normal overnight decline: 1,776 aircraft in the 0500Z bin, against 2,725 at the same time Thursday, 35% below. The gap is narrowing mainly because Thursday's late-evening traffic was also thinning out.

FAA advisories (database):

Dallas–Fort Worth (from 0341Z), LAX and O'Hare remain under airport ground stops.

Europe. Eurocontrol removed its notice suspending US-bound departures from its website, according to DPA. The suspension covered flights scheduled 2200Z Friday to 0500Z Saturday. DPA expects "significant disruption" to Saturday's transatlantic schedule because aircraft and crews are out of position. Hong Kong's NOTAM holding departures into US Pacific airspace still runs to about 0800Z.

Saturday. According to NBC:

• Southwest is restarting "a limited number of flights this evening" to "position our operation for Saturday morning", with schedules "adjusted based on the location and availability of our Crews and our aircraft".
• American expects "residual delays and cancellations tonight and into tomorrow" and is prioritising non-hub and international flights.

ABC, citing FlightAware, put Saturday cancellations at "nearly 800" as of about 2330Z Friday. That figure is several hours old.

Traffic has levelled off at about 1,950 aircraft over the lower 48 (0410Z), against 3,620 at the same time Thursday. That is 46% below Thursday, narrowing as the normal late-night traffic thins out.

Overheard (United dispatch, 0053Z, during the stop): "HEY, JUST AN UPDATE TO SAY I HAVE NO UPDATES."

• FAA statement. The FAA said that before lifting the stop "we thoroughly tested our systems to confirm they were stable and that operations remain reliable", and told travellers to check with their airlines (NBC). It still has not named a cause.
• Trump said the outage does not appear to be a cyberattack or related to AI, calling it "a bunch of old broken stuff". This is per Fox News; HEXBIRD has not found a transcript.
• Duffy repeated his call for money: "This is an emergency. I want Congress to give us emergency funding" (Fox).
• Congress. Senators Cruz and Cantwell are asking what went wrong, including "Was there some sort of fail-safe?" (Fox). No hearing or formal investigation has been announced.
• Air Canada cancelled all US flights for the rest of Friday evening (Fox). Combined with the Hong Kong NOTAM and Europe's suspension, which runs to 0500Z, inbound international traffic will stay thin overnight.

New entries in the FAA Command Center's advisory database:

DFW's stop follows American's 0222Z warning that flights were waiting more than three hours for a gate there. Its departures had been recovering, reaching 41% of normal at 0245–0325Z. The stop's stated reason has not been published.

LaGuardia has restarted. HEXBIRD's feed shows its first departure since 2330Z at 0326Z, Endeavor 5560 (a CRJ-900), climbing north. Three Southwest 737s followed at 0328Z, 0336Z and 0348Z: flights 432, 2560 and 2583. All four had been visible parked at LaGuardia's gates throughout the gap, so the receivers had not lost the airport. They waited about 4 hours to leave, and two hours after the national stop was lifted. No FAA advisory explains the gap.

Aircraft over the lower 48 reached 1,879 in the 0340Z bin.

• Mexico is resuming US-bound flights. Mexico's civil aviation agency (AFAC) says the FAA notified it at 7:44 p.m. local time (0144Z) that US operations had resumed. AFAC says flights from Mexico to the US "are expected to resume gradually over the coming hours." This is AFAC as reported by Fox News; HEXBIRD has not found AFAC's own statement. Europe's suspension of US-bound departures has not been reported lifted.
• Duffy says the outage was partial. According to Fox News, he said the FAA "did not lose all radar or telecom", and that telecom problems began at 3:36 p.m. Eastern (2036Z). HEXBIRD's audio and datalink show Chicago Center in trouble from about 2006Z. The two times probably describe different stages: a local failure in Chicago first, then the network-wide failure.
• The FAA's new AI routing tool, SMART, denied as the cause. The FAA expanded the tool to all 22 en route centres on 10 November, which made it a target for speculation. Its developer, Air Space Intelligence, said: "The current ground stop is not based on or a result of the SMART system." Homeland Security Secretary Mullin said earlier: "You can't rule out anything at this point." (Latin Times)
• Airlines. United is "resuming operations, including some Friday night flights" (NBC). JetBlue cancelled the rest of its evening except Europe-bound departures from JFK and Boston, and expects "additional cancellations" Saturday. That fits JFK recovering first and Boston easing back after 0245Z.

The restart sped up sharply after 0245Z. Across 27 large airports, airline departures in the 40 minutes from 0245Z to 0325Z were 61% of the same window on Thursday (269 against 443). Between 0130Z and 0245Z they had been only 19%.

• The hubs that had stalled are moving.
  • Charlotte went from 4% of normal to 91% (10 of 11).
  • Dallas–Fort Worth went from 4% to 41%.
  • Atlanta went from 10% to 54%.
  • LAX is at 69%, despite its 0242Z ground stop.
• Several airports are above normal for the hour, including Midway, BWI, Portland, Minneapolis and Tampa. These are delayed evening departures leaving late, not extra flights.
• O'Hare is still at about 20%. Its stop was reissued at 0308Z (Advisory 025), and United expects an update at 0346Z. Seattle's (023) and Minneapolis's (024) stops were also reissued. Alaska's dispatch told a crew Seattle's stop "will officially cancel at 0330Z".
• LaGuardia: no takeoffs or landings visible since 2330Z. (Update, 0400Z: departures resumed at 0326Z; see the 0400Z entry.) Before the outage HEXBIRD's feed showed about 30 aircraft per half-hour at low altitude around LaGuardia. That fell to zero by 2330Z and has stayed at zero for four hours, including after the stop was lifted. The same receivers still see aircraft parked at LaGuardia's gates, so this does not look like a coverage gap. No FAA advisory explains it. The likeliest explanation, which HEXBIRD has not confirmed, is that airlines cancelled LaGuardia's remaining short-haul evening schedule.

Air traffic over the lower 48 has levelled off at about 1,600 aircraft (0310–0320Z), about 61% below the same time Thursday. Departures recover faster than this count does, because so many of the evening's flights were cancelled outright.

New entries in the FAA Command Center's advisory database since the last update:

At 0249Z United told a crew that the O'Hare stop, first due to end at 0245Z, now has an "update time of 0346Z". Departures from O'Hare are still being cleared.

The reason appears to be space on the ground. NBC cites a source saying O'Hare was "nearing capacity" for parked aircraft. Newark tower described "a whole mess" with controllers "running out of space". American's dispatch cited "ground saturation" at its hubs earlier. HEXBIRD has seen no message describing new radio or radar trouble. The FAA's advisory texts, which would state a reason, are not loading from its server.

Traffic keeps climbing. There were 1,318 aircraft above 1,000 ft over the lower 48 in the 0250Z bin. That is double the 0130Z low of 644, but still about 70% below the same time Thursday (4,524).

An hour after the FAA cancelled the national stop, the restart is very uneven from airport to airport. HEXBIRD counted airline departures at 27 large airports from 0130Z to 0245Z, and compared each with the same 75 minutes on Thursday evening:

• New York's JFK is back to normal for this hour. Its evening departures are mostly long-haul flights to Europe and Asia, which were the first to be released.
• American and Delta's big hubs have barely moved. Dallas–Fort Worth has had 3 of a normal 69 departures, Charlotte 2 of 47, and Atlanta 4 of 40. This is consistent with American's dispatch message about "ground saturation" and flights waiting more than three hours for a gate at DFW.
• San Diego and LaGuardia: no airline departures. San Diego has been under a new FAA ground stop since 0204Z (Advisory 014).
• O'Hare is at 16%, under its own ground stop since 0141Z.

The same view of the sky around four airports at 0245Z, at the same scale (screenshots from airplanes.live; map data © OpenStreetMap contributors):

Method: departures are aircraft with airline callsigns climbing through 1,500 ft within 10 km of each airport. Denver, Salt Lake City and Las Vegas are left out because their field elevation defeats this filter. The comparison window is in UTC, so Thursday's figures are the same clock hours on an ordinary Thursday evening.

The FAA Command Center's advisory database shows that the national stop was followed first by cancellations, then by new airport-level stops:

The program cancellations confirm what United's dispatchers told crews at 0136Z: all ground delay programs were lifted. The new stops are airport-specific "CDM" ground stops, not a return of the national stop. The FAA's server returned "NO Advisory" for each text, so the stated reasons are not yet known.

One likely reason is gate gridlock rather than another radio failure. At 0222Z American's dispatch told a crew: "GROUND STOP HAS BEEN LIFTED BUT WE CANT RLSE ANY FLIGHTS INTO AA HUBS DUE TO GROUND SATURATION … MANY FLIGHTS OVER 3 HOURS TRYING TO GET INTO GATE IN DFW." This is an airline relay. HEXBIRD has found no message describing a new communications or radar outage.

Crews are starting to run out of duty time. A SkyWest crew bound for San Francisco messaged at 0230Z: "WE WONT BE ABLE TO MAKE THE EDCT TIME OF 0250Z. GOIN TO TIME OUT."

The Pacific is still held from the Asian side. At 0212Z a China Southern aircraft received Hong Kong NOTAM A2640/26 by ACARS. It says that, at the request of Taipei and Japan control centres, "GROUND STOP IS APPLIED TO ALL DEPARTURES ENTERING PAZA AND KZAK", meaning Anchorage and Oakland oceanic airspace. It runs from 0030Z to an estimated 0800Z, well after the US cancelled its own stop.

Traffic is still climbing. Aircraft above 1,000 ft over the lower 48 rose from 644 at 0130Z to 894 in the 0220Z bin, against about 4,900 at the same time Thursday.

The full cancellation advisory. The FAA's database lists Advisory 005 with only its title. An American Airlines aircraft (N979UY) received the full text by ACARS at 0124Z. It is stamped 0119Z, with an event time of 0116–0130Z, "FACILITIES INCLUDED ALL", and no reason given:

ATCSCC ADVZY 005 DCC 11/14/2026 CNX NATIONWIDE GROUND STOP … REMARKS THE FAA COMMAND CENTER NATIONWIDE GROUND STOP HAS BEEN CANCELLED.

"Good enough to lift." A Delta-format ATC desk message sent at 0119:52Z, and repeated until 0132Z:

COMMS ARE OVERALL IN GOOD HEALTH. COUPLE OF OUTLIER ISSUES STILL BEING WORKED BUT GOOD ENOUGH TO LIFT THE GROUND STOP

It does not say which facilities still had problems.

No ground delay programs, per United's dispatchers. These are airline relays; no FAA advisory confirms or contradicts them:

• 0136Z: "INFORM ALL GDPS LIFTED DUE TO LOW DEMAND FROM CANCELATIONS/DELAYS"
• 0156Z: "NO GDPS IN EFFECT AT THIS TIME / EVERYTHING IS RUNNING BEHIND"

So the restart is being limited by crews, aircraft and cancelled schedules, not by FAA metering. This matches Duffy's comment that recovery depends on crew availability.

One exception. At 0148Z, United told a Dallas–Chicago flight there was a "GROUND STOP UNTIL 0245Z FOR UAL TO ORD - SHOULD BE LIFTED BY THE TIME YALL ARE READY ANYWAY". HEXBIRD found no ATCSCC advisory for it.

Overheard (United dispatch, 0127Z): "STILL NO WORD ON HOW THINGS WILL RESTART. MY ENTIRE DESK NEEDS NEW RELEASES. EVERYTHING IS OUT OF WHACK."

At a press conference Friday evening (about 0100–0130Z), Transportation Secretary Sean Duffy gave the first on-the-record explanation:

"We have old switches, old routers, we use 1980s little copper lines … It's an old system that went down. It went down everywhere. It got overloaded." (Yahoo News)

"Our switches, our routers, actually got overloaded with data." … "we experienced instability for our radar and our communications in our centers and our TRACONs across the country." (ABC7 New York)

What this adds and leaves open:

• Radar is now on the record. Until now radar problems were only reported secondhand by airline dispatchers. Duffy confirms instability in radar as well as communications.
• Routers and switches, overloaded. This is consistent with the CNN-reported "router problem" and with the network-update account CBS's sources gave. Duffy did not name L3Harris, a software update, or Chicago Midway.
• His times differ from the record. Duffy put the start "just after 3:30 p.m." Eastern (about 2030Z) and the reopening at "8:15 p.m." (0115Z). HEXBIRD's audio shows Chicago Center frequencies failing from about 2006Z. The FAA's own Advisory 107 backdates O'Hare's stop to 2010Z, and the cancellation advisory is stamped 0119Z. His times may describe the national-level failure rather than the first local symptoms.
• Not a cyberattack, but not ruled out. Homeland Security Secretary Mullin: "It appears that this was mechanically driven. However, we're still looking, so we're not going to rule that out." Also: "The public was never at danger."
• Recovery. Duffy says it will be "slow" and depends on crews: "hopefully tomorrow we are going to start to see far better movement." He used the moment to call for $50 billion in ATC modernization.
• Cancellations. NBC charts more than 5,300 cancellations by 0120Z.

For the first time since the outage began, the number of aircraft in the air over the lower 48 is rising. ADS-B counts of distinct aircraft above 1,000 ft, per 10 minutes:

Airline climb-outs across the lower 48 rose from about 25 per 10 minutes before the 0119Z cancellation to 43 in the 0200Z bin. Traffic is still about 85% below a normal Friday night, and many of tonight's flights are already cancelled. The low came at 0130Z, 11 minutes after the stop was lifted, as the last flights from before the stop landed and the first new departures had not yet climbed.

Half an hour after the cancellation, ADS-B shows the first passenger jets leaving on what look like domestic legs. Destinations are inferred from origin, heading and aircraft type and have not been confirmed by datalink:

International releases continue alongside them: Delta to Amsterdam from Orlando, and Delta widebodies from Detroit, Seattle and JFK. FedEx 1316 from Burlington at 0134Z remains the first domestic departure HEXBIRD has seen. Correction, 0215Z: this entry originally said departures were being metered through ground delay programs. United dispatch messages at 0136Z and 0156Z say the opposite: all GDPs were lifted "due to low demand from cancellations/delays" (see the 0215Z entry).

The first domestic airline departure HEXBIRD's ADS-B shows after the FAA cancelled the stop at 0119Z is a cargo flight. FedEx 1316, a 1992 Boeing 757-200 (N783FD), lifted off from Burlington International at 0133:48Z. It was crossing Lake Champlain southwest at 16,000 ft four minutes later. Burlington to anywhere on that heading is a domestic leg.

Every other airline departure since the lift has been international or bound for Hawaii or Alaska: United and Delta widebodies to Europe, and Alaska to Anchorage. The one ambiguous case is Envoy 3756 from Miami at 0127Z, heading southwest on a track that fits either Key West, which would be domestic, or Cancún.

The first scheduled domestic passenger departure is still to come. Airlines told crews to board at 0117–0123Z.

Airline dispatch began relaying the cancellation within minutes of Advisory 005:

• Delta, 0117Z: "ATC GROUND STOP HAS BEEN LIFTED. PLEASE HEAD TO GATE AND BOARD WHEN READY."
• United, 0121Z: "NATION WIDE GROUND STOP LIFTED. MORE DETAILS TO COME FOR GDPS AND SPECIFICS." GDPs are ground delay programs, so departures will be metered, not released all at once.
• Another carrier, 0123Z: "GROUND STOP LIFTED."

Crews are still asking ("IS IT LIFTED IF SO R U WORKING EDCT"), so the restart will run through assigned departure slots. Reports on social media say Detroit's ground controllers are "back to business". As of 0123Z, HEXBIRD's ADS-B shows no domestic departures yet: passengers have to board first. The first domestic climb-outs should appear in the coming half hour.

The FAA's ATCSCC advisory database for 14 November lists:

005  DCC  11/14/26  CNX NATIONWIDE GROUND STOP  11/14/26 01:19

"CNX" is the Command Center's abbreviation for cancellation. The national departure stop in effect since 2053Z (Advisories 111 and 120) has been cancelled as of 0119Z, about 2 hours 40 minutes before its scheduled 0400Z expiry and about 5 hours 10 minutes after the first radio trouble at Chicago Center.

Caveats.

• We don't have the text. The FAA server is returning "NO Advisory" for Advisory 005, so the conditions of the cancellation are not yet known. These would include any remaining restrictions, gradual release rates or facilities still excluded. The title above is from the FAA's own list.
• Datalink hasn't relayed it yet. HEXBIRD has not yet seen airlines pass it on.
• No domestic departures yet. As of 0121Z ADS-B still shows only international, Hawaii and Alaska departures. These include Aeroméxico 471, the first southbound release out of Houston Intercontinental, at 0119Z.

A restart after a stop this long will be slow. Crews are out of duty time, aircraft and gates are out of position, and more than 4,200 flights are already cancelled. HEXBIRD is watching the hubs for the first domestic departures.

Other advisories since midnight UTC: an operations plan (001), a "ZDC NRP suspension" for Washington Center (002, meaning flights there must follow published routes rather than fly direct), and an oceanic route closure for New York Center (003).

The FAA's ATCSCC advisory database confirms what the audio showed. Advisory 107 put O'Hare under a ground stop effective 2010Z, reason "EQUIPMENT / OUTAGE … COMMS ISSUES". It was issued at 2028Z, 25 minutes before the national stop. Advisory 117 (2121Z) describes the event as a "nationwide comms failure".

• 4,238 US cancellations and 10,079 delays as of 7:30 p.m. Eastern (0030Z), per FlightAware figures cited by NBC. ABC also reports more than 4,000. The count rose by about 900 in 40 minutes.
• The night may be written off. CNN, citing an airline source, reports major airlines "could shut down operations for the rest of tonight", and says the source described router problems that "cascaded nationwide". This is consistent with JetBlue's 0008Z message to crews cancelling its remaining flights.
• The White House: NBC reports the President is receiving "constant updates". The stop is expected to "run through at least 11 tonight" Eastern, which is 0400Z and matches Advisory 120.
• Still nothing on the record from the FAA, DOT or L3Harris on the cause. No outlet has the text of an FAA NOTAM closing US airspace to inbound international flights, although United dispatch has been telling crews since 0025Z that one is coming.

The inbound closure. United dispatch told a crew at 0035Z: "US AIRSPACE IS CLOSING TO ALL WORLDWIDE TRAFFIC BY NOTAM. SO NO GOOD NEWS AND NO INFO AS TO WHY OR HOW TO FIX." At 0025Z the same desk said it "WILL BE CLOSING BY NOTAM TO WORLDWIDE INTERNATIONAL FLIGHTS COMING BACK." HEXBIRD has still not seen the NOTAM text itself. A WestJet crew at 0025Z reported hearing "a Cathay and a German cargo" handed off to US control, so flights already airborne are still being accepted.

Departures 0028–0043Z (ADS-B): 16 airline aircraft climbed out of the 30 monitored airports. All are international or offshore:

• Newark: Aer Lingus, SAS, United 134
• JFK: American 100, Air France
• O'Hare: a Cargolux 747, United 970 (north toward Europe), Austrian
• Dulles: United 946 and 918
• Miami: British Airways' A380 and Icelandair; American 1833 southeast to the Caribbean
• Atlanta: Air France and Delta 72
• Seattle: Alaska 223, a 737 MAX 9, which turned southwest over the coast on a Hawaii heading

Houston Intercontinental and Hobby have had no airline departures at all since 2200Z, despite the reported southbound release.

Aircraft over the lower 48: 787 at 0040Z, against 5,907 at the same time Thursday. That is −87%, and the gap keeps widening as the last domestic flights land and nothing replaces them. Airport ATIS broadcasts still say the next ground-stop update is at 0400Z.

From 0006Z to about 0028Z, 23 airline aircraft climbed out of the 30 monitored airports. Every one was bound overseas or for Hawaii. A sweep of the whole lower 48 found no domestic airline departure anywhere.

• Transatlantic: United and Air France from Newark and Dulles; British Airways, Lufthansa and Delta from Boston; Aer Lingus, Delta, American and Brussels from JFK; Aer Lingus from Philadelphia and O'Hare; Lufthansa, Virgin and American from Miami; and Delta 214 from Atlanta, an A330-900 that turned east on a transatlantic heading. That is Atlanta's first departure of the evening.
• Hawaii: Delta and American from LAX, Delta from Seattle, and Alaska 2693 from Ontario, California, the first Hawaii departure from a non-hub airport.
• Houston Center's southbound release has produced no visible departures yet from Houston Intercontinental or Hobby. Arrivals are still visible there, so receiver coverage is fine.
• Other flights: medical-lab couriers and flight-school traffic flying under visual rules. No emergency or lost-comms squawks since 2355Z.

Traffic over the lower 48, against a fairer baseline. Earlier entries compared tonight with early afternoon, which overstates the drop because traffic falls every evening. Against the same time 24 hours earlier:

Against the early-afternoon average the figure is about −88%. Both describe the same emptying sky.

• Airports full. Two NOTAMs in the FAA status feed close airports to diverting aircraft. Reagan National: !DCA 11/261 DCA AD AP CLSD TO DIVERSION ACFT, 0004Z to 1100Z. Fort Lauderdale: !FLL 11/137 … CLSD TO DIVERSION ACFT DUE TO CAPACITY, 2323Z to 0900Z. These follow the full gates reported at Reagan National, O'Hare and Seattle.
• Mexico. The aviation authority AFAC has ordered aircraft at Mexican airports with US-bound flights to stay on the ground until US authorities confirm it is safe (El Financiero, Excélsior). Together with Eurocontrol's suspension, the two largest sources of inbound international traffic have now stopped sending flights.
• JetBlue told crews at 0008–0010Z: "ALL REMAINING FLIGHTS FOR TODAY WILL BE CANCELED. PLEASE CONTACT CREW SERVICES FOR SCHEDULE MODIFICATIONS OR QUESTIONS REGARDING HOTELS." This is the first systemwide end-of-day cancellation by a major carrier seen in datalink.
• Canada's wording narrows. Edmonton's ATIS at 0011Z now reads "GROUND STOP TO THE LOWER FORTY EIGHT UNITED STATES AND MEXICO LOCATIONS". The earlier version said "ALL UNITED STATES". That excludes Alaska and Hawaii, matching what has been flying.
• Still pending. United at 0008Z repeats that a "WORLDWIDE GROUND STOP FOR ALL FLTS INTO THE U.S." is expected "BY AROUND 0040Z". HEXBIRD has seen no NOTAM text yet. Secondhand reports suggest more Europe releases from Seattle and Miami.
• Cause and Congress. The Wall Street Journal (as quoted on X; paywalled) joins CBS in tying the outage to a "telecommunications network overseen by L3Harris Technologies" that "handles crucial radio frequencies". There is still nothing on the record from L3Harris or the FAA. Senator Maria Cantwell says the Commerce Committee will review "technology issues related to how planes communicate through primary frequencies, backup frequencies".

Datalink traffic this afternoon has been mostly terse and practical. Some of it was not. At 2124Z a United dispatcher, sending fuel numbers to a Las Vegas–Houston flight in between phone calls:

FAA JUST RLS NATIONWIDE AIRBORNE HOLDING FOR ALL FLIGHTS DUE TO
MULTIPLE FREQ ISSUES.... PLEASE STANDBY FOR ALT BURNS I AM GOING IN
ORDER OF PRIORITY IN BETWEEN 100 CALLS :P
LMK IF YALL NEED ANYTHING AND HAPPY FRIDAY THE 13TH TO ALL THAT ARE
CELEBRATING AGAINST THEIR WILL

One minute later, an Allegiant crew to its dispatcher:

APPARENTLY IT IS A GOOD IDEA TO HAVE LOTSA EXTRA GAS FRIDAY THE 13TH.

And at 2336Z, a Republic crew stranded in Madison, after seeing their flight cancelled with 81 people in the crew-scheduling queue: "ITS ALL GOOD WERE LIVING THE DREAM HAHA".

Personal names removed.

• Air Space Intelligence, which makes the FAA's "SMART" traffic-management tool, said on the record: "The current ground stop is not based on or a result of the SMART system" (The Register).
• Hawaii DOT (1:05 p.m. HST, 2305Z): Hawaiian and Alaska Airlines "have confirmed all west coast flights will resume… All inter island flights remain active." That matches the West Coast–Hawaii releases seen in ADS-B (ABC News live).
• Radar: CNBC cites an internal Alaska Airlines message describing "communications and radar problems". Like earlier dispatcher mentions of radar, it is secondhand. The FAA has not said radar was affected.
• Still nothing on the record from the FAA or L3Harris on the cause, and no outlet reports the stop lifted.

• United's ATC desk, 0001Z: "ZHU FLTS RLSD TO MEXICO, S.AMERICA, C.AMERICA BUT NOT CARIBBEAN." Houston Center can now release departures south, the first named en route center to get a regional release. The same update says "MANY ATC FREQS STILL INOP" and repeats: "GLOBAL GRND STOP VIA NOTAM EXPECTED FOR ALL FLTS TO U.S. BY AROUND 0040Z, FLTS ALREADY BEING STOPPED."
• O'Hare's first departure since 2016Z: British Airways 20R (787-10) climbed out at 0004Z, heading due north on a Canada routing to London. In the same window, international releases continued from JFK (Lufthansa, ANA, Virgin, Swiss, Delta), Newark, Dulles (Iberia, KLM), Philadelphia (British Airways), SFO (United 857 and United 300) and Seattle (Delta 69). An Atlas Air 747 freighter left Miami northeast over the Atlantic.
• Still no domestic airline departures anywhere in the lower 48. Aircraft airborne over the lower 48: 1,034 at 0000Z.

With an inbound halt expected around 0040Z, are flights already over the oceans turning back or diverting? Based on ADS-B and datalink through 0007Z: they are continuing to their US destinations.

Landing as planned. Widebodies arriving at US gateways from 2300Z to 0007Z: aircraft between 3,000 and 200 ft and descending within 15 km of the airport.

No ocean turnbacks. HEXBIRD's ground-based ADS-B found no long-haul aircraft over the Atlantic or Pacific that reversed after heading toward the US since 2200Z. Mid-ocean coverage is thin, so HEXBIRD also checked satellite ADS-C position reports, as shown by ADS-B Exchange at 0009Z. Between 15°W and 60°W, 18 aircraft above 20,000 ft were still westbound:

• Passenger: British Airways 183, Turkish 11, TAP 211 and 203, Aeroméxico 26 and 4, Avianca 121
• Cargo and other: FedEx, Ethiopian and other freighters, plus business jets

None was on a reversed track. ADS-C positions are typically 5–20 minutes old.

No Atlantic diversion wave. HEXBIRD saw no widebody arrivals at the usual transatlantic diversion airports (Gander, St. John's, Halifax, Keflavík, Shannon). Toronto, Montréal and Vancouver arrivals are at normal levels. A crew reported hearing on the radio that "European flights to the US are now being diverted to YYZ/YUL". Arrival counts at those airports do not show it. (Qantas 75 at Vancouver is its regular Sydney–Vancouver flight.)

The diversions are domestic. Crews and dispatchers describe diversions away from gridlocked hubs, not away from the US:

• United's desk at 2207Z: "ALL FLIGHTS WITHIN AN HOUR OF ORD ARE BEING DIVERTED TO OTHER LOCATIONS." United 424 Boise–O'Hare diverted to Des Moines.
• Delta 554 Seattle–Atlanta diverted to St. Louis. A Delta Los Angeles–Boston flight diverted to Cleveland.
• An American flight to Reagan National was told at 2121Z to "DIVERT DUE TO GRIDLOCK".
• Seattle is clearing gates for arrivals. American dispatch at 2354Z: "ALL GATE ARE FULL. SEA IS DEPLANING FLIGHTS AND THEN PUSHING THEM OFF TO MAKE ROOM FOR YOU."

Cirium data cited by CNBC counts about 600 diversions among roughly 11,000 flights scheduled after 4 p.m. Eastern.

The inbound halt, when it comes, should stop flights from departing overseas airports for the US. Flights already airborne will still land, which is how the FAA's "case by case" handling has worked all afternoon. Overseas, British Airways has cancelled its evening Heathrow–New York flight, and Manchester warns that Saturday-morning Virgin Atlantic US flights may be disrupted.

• Eurocontrol suspension confirmed. Reuters reports Eurocontrol's website shows "All US-bound traffic departing from Eurocontrol member states has been suspended" at the FAA's request, citing technical problems. That covers flights from all 42 member states. HEXBIRD had held back the earlier report on X by @Shauns_Aviation (2318Z) until it could be confirmed. The 2200Z–0500Z window in that post still has no second source. Reuters gives no end time. Together with United's 2350Z note of a "worldwide ground stop for all flts into the U.S." around 0040Z, the US is now shutting the door on inbound traffic as well as outbound.
• Cancellations. FlightAware shows more than 3,300 US cancellations at about 2350Z, up from about 1,800 some 45 minutes earlier (ABC Australia live). CBS puts delays at about 10,000.
• Airports at capacity. NBC cited a source at about 2230Z saying Reagan National was at capacity and O'Hare was close. HEXBIRD's surface count shows O'Hare was there. NAV CANADA says "all Canadian systems are operating and can support diverted airplanes."
• Exempt operations confirmed. Alaska Airlines says flights within Alaska and within Hawaii "are not impacted", matching what HEXBIRD's ADS-B has shown all afternoon.
• Congress. NBC reports senior lawmakers had not been briefed. Senator Tammy Duckworth: "Whatever led to the nationwide ground stop will warrant a thorough and complete investigation."

Still nothing on a lift. The FAA's latest line is still that flights will depart "as enroute facilities recover". Neither the FAA nor L3Harris has commented on the record about the cause.

United dispatch began giving crews a time for the inbound halt at 2350Z:

WORLDWIDE GROUND STOP FOR ALL FLTS INTO THE U.S. TO COME OUT BY
AROUND 0040Z DUE TO CONTINUED ATC FREQ PROBLEMS.

Earlier, at 2334Z, the same desk had told crews: "THE FAA HAS ANNOUNCED THAT THEY ARE NOT ALLOWING INTERNATIONAL FLIGHTS TO ENTER THE USA AT THIS TIME. THE EXPECTATION REMAINS THAT THE GROUND STOP WILL LIFT AT 0400Z."

These are airline relays. HEXBIRD has not seen the FAA notice itself. If it is issued as described, flights departing for the US from anywhere in the world would be held at their origin. Flights already over the ocean would continue.

Other datalink items since 2320Z:

• Delta flight control, 2326Z: "COMMAND CENTER WORKING WITH NAVCANADA TO RELEASE OUR EUROPE FLIGHTS NORTH BOUND." That means routing Europe departures north through Canadian airspace and around impaired US facilities.
• Frontier dispatch, 2324Z: "FAA SAID WILL START COORDINATING RELEASE OF INDIVIDUAL FLIGHTS WHEN SYSTEMS IMPROVE BUT WE HAVEN'T SEEN ANY MOVEMENT YET."
• Winnipeg ATIS (2300Z): "GROUND STOP FOR ALL U/S AIRPORTS AND AIRSPACE."
• A Canadian operator, 2327Z: "THE MAJORS - YVR YUL YYZ AND YYC WERE INITIALLY IN A GROUND STOP OF THEIR OWN… RAMP IS CONGESTED." That suggests the Canadian stops were about ramp space, not equipment.

No ATCSCC advisory newer than 120 has appeared.

From 2340Z to 2354Z, 20 airline aircraft climbed out of the 30 monitored US airports. Every one was international or Hawaii-bound:

• Boston: SAS 928, TAP 218
• JFK: Aer Lingus 104, Air France 3, Delta 182
• Newark: United 40, United 30, an Amerijet freighter
• Dulles: United 260, United 989, Lufthansa 419, Austrian 42
• LAX: Korean Air Cargo 224, Philippine 123, plus United 1431 and American 59, both heading west over the Pacific (Hawaii by heading)
• SFO: United 809, JAL 57

JAL 57 is the Tokyo flight that sat on the SFO ramp all afternoon. It finally left at 2351Z.

Still no domestic airline departure from any of the 30 airports or anywhere else in the lower 48. Departures from Toronto Pearson are moving again, including Air Canada and a Lufthansa flight.

Aircraft in the air over the lower 48: 1,162 at 2345Z, down 85% from early afternoon (about 7,890). The decline has slowed to about 40 aircraft per five minutes, as the last domestic flights land. No emergency or lost-comms squawks have appeared since 2330Z.

SpaceX's Starship launched from Texas this afternoon while the national ground stop was in force. Spaceflight is managed through its own airspace closures, not the departure stop. Scott Manley (@DJSnM) at 2311Z:

"Go for orbit. No go for domestic air travel."

The upper stage reached orbit. Manley reports the booster failed during its return, apparently from a tank pressurization problem. A Delta dispatcher told crews at 2301Z that "ALL ROCKET LAUNCH RELATED AIRSPACES ARE RELEASED… BUT THE USA IS STILL IN ATC GROUND STOP."

Two news organizations now have sourced accounts of the cause. They differ in detail but point at the same system:

• CBS News, citing sources: an update to the private communications network that connects the air traffic control system forced it to reboot, and it crashed when it came back up. The network is operated by L3Harris, which had not responded to CBS.
• CNN, as relayed by other outlets (example): the FAA told airlines that a network router problem, believed to have started at Chicago Midway, caused the nationwide stop.

Neither account is an on-the-record FAA statement. Earlier reports said the FAA disputed a software-update explanation. The two accounts could both be true, for example an update that broke a router. HEXBIRD has found nothing that reconciles them.

How this fits HEXBIRD's own record. Both accounts put the origin in the same place as the radio evidence:

• The earliest trouble HEXBIRD found was on Chicago Center frequencies at about 2006Z. A crew could transmit but heard no reply, and a stuck mic was reported at 2012Z.
• By 2020–2024Z Chicago controllers were saying the approach facility "lost their frequencies" and blaming "equipment issues over at the TRACON".
• O'Hare and Midway were ground-stopped together, before the national stop. O'Hare's last departure was at 2016Z, the earliest of any hub.
• At 2102Z a Chicago controller described Rockford, Madison and Milwaukee approach as "ATC zero", all Chicago-area facilities.
• Kansas City Center was working normally at 2020Z and pointing crews toward Chicago as the problem.

A fault on the network around Chicago, spreading or being propagated to other facilities, would produce this sequence. A simultaneous nationwide failure would not.

Status check: news reports say the FAA's airport status page stopped listing the national ground stop at about 2341Z. HEXBIRD's checks of that feed never showed a national ground-stop program at any point today, only per-airport delay entries. Most of those disappeared by 2251Z, and only Houston Intercontinental remained at 2342Z. So the page is not a reliable signal either way. No lift has been announced, and ADS-B still shows no domestic departures.

United's ATC desk issued a new update at 2326Z, relayed to crews at 2329Z. The new items are the ones marked with asterisks:

NATIONWIDE DEPT STOP STILL IN EFFECT, TILL 0400Z FOR NOW PER
 ADVZY 120, MULTIPLE ATC FREQS STILL NOT WORKING. ...
 *EXCEPTIONS BELOW*. MEDEVACS EXEMPT. ...
 INTL DEPTS: W.COAST-HAWAII & PACIFIC RLSD, BOTH ANC & OAK CTRS OPEN.
 EWR-EUROPE RLSD.
 IAD-EUROPE RLSD VIA SWANN-RBV (AVOID N90 DUE FREQ PROBS).
 INTL ARVLS: HAWAII-W.COAST RLSD FOR NOW *BUT NEW NOTAM COMING
 SOON TO STOP ALL INTL FLTS TO U.S.* GUM FLTS STILL RLSD.

What it adds:

• Inbound international flights are about to be stopped. That would turn a departure stop into a halt on arrivals from abroad too. It matches an earlier claim on X, which HEXBIRD held back (@Shauns_Aviation, 2318Z), that Eurocontrol would suspend flights from Europe to the US from 2200Z to 0500Z. The airline desk and the Eurocontrol report are independent of each other. No NOTAM text has been seen yet.
• New York TRACON (N90) still has radio problems. Dulles–Europe flights are routed around it via the SWANN and Robbinsville (RBV) fixes. This is the first named facility still impaired more than three hours after the outage began.
• Anchorage Center has reopened. At 2240Z the same desk had it closed to Pacific transits. Pacific flights may now route through Anchorage Center as well as Oakland's oceanic airspace.

ADS-B confirms the international releases are flowing. Since 2330Z, departures include Delta 156 from JFK; Delta 224, Aer Lingus 13K and SAS 928 from Boston; Air France from Newark; and Singapore 11 from LAX. Domestic departures are still at zero. The FAA status feed no longer lists the Toronto and Montréal ground-stop programs; both had expired by 2330Z.

This shows the queues behind our earlier count of aircraft idling on the field. Lines of jets wait nose-to-tail on the taxiways along O'Hare's west side and across the south airfield, with more clustered at the northwest and terminal ramps. Nothing is moving toward a departure runway. The few aircraft arriving have to fit around them.

The first reporting on a cause is out, and it conflicts:

• Bloomberg: the FBI does not believe the outage was a cyberattack or criminal act, and one line of inquiry is whether a software update caused it.
• Later reports say the FAA denies that a software update caused the outage. HEXBIRD has not seen the FAA's own wording.
• Verizon says its network is working normally and it knows of no issue tied to air traffic control.
• Secretary Mullin said the Cybersecurity and Infrastructure Security Agency (CISA) is examining whether the FAA's new "SMART" traffic-management tool played a role. CNN reported no apparent connection. The tool's developer has issued a statement denying any link, as relayed by @airplaneian.

What HEXBIRD's own data supports. The failure was in air-to-ground radio and the links behind it. It hit Chicago Center first (from about 2006Z), then approach controls around Chicago and at least one New York-area sector (from about 2028Z). Approach controls and towers elsewhere largely kept working. That pattern fits a fault in the network carrying radio traffic between facilities and remote transmitter sites. The FAA runs that network under its FAA Telecommunications Infrastructure (FTI) program, operated by the contractor L3Harris. No official source has named FTI, L3Harris or any specific update. Treat "software update" as an unconfirmed line of inquiry.

A new Command Center advisory, relayed verbatim by United dispatch at 2304Z. It is the first new ATCSCC advisory number since 116 at 2120Z:

ATCSCC ADVZY 120 DCC 11/13/2026 NATIONWIDE GROUND STOP
EVENT TIME: 13/2245 - 14/0400
DESTINATION AIRPORT:ALL
FACILITIES INCLUDED: ALL
EXPECT UPDATE:0400Z
REASON: COMMUNICATIONS FAILURE
REMARKS: THE FAA COMMAND CENTER GROUND STOP REMAINS IN EFFECT. AS
ENROUTE FACILITIES RECOVER, FLIGHTS WILL BE ALLOWED TO DEPART
THROUGH COORDINATION WITH THE AIR TRAFFIC CONTROL SYSTEM COMMAND
CENTER.

What is new: the stop is reissued with a formal reason, "communications failure". The FAA states its release plan: flights go center by center, as each recovers, through case-by-case coordination with the Command Center. United's desk describes the same plan as "a tiered approach for releasing more traffic as limitations are reduced… timing for releasing traffic is still unknown."

Airport ATIS broadcasts now spell out the exceptions locally. Ontario, California (2253Z): "except westbound oceanic flights to Hawaii and further." Portland (2253Z): "except law enforcement and medevac." Detroit (2327Z): "No departures authorized until further notice."

West Coast–Hawaii releases are visible in ADS-B. Alaska 353 left Portland at 2321Z and Alaska 362 left Seattle at 2323Z, both heading southwest over the Pacific. More transatlantic flights also left: Air France from Boston at 2320Z and United 956 from Newark at 2325Z.

Retired airline captain Juan Browne (blancolirio) warned early on that hubs would "mog out", reaching their maximum number of aircraft on the ground with nowhere to park new arrivals. He also pointed to the clock: "You can only keep the passengers stuck on an airplane for so many hours before you start getting fines." His video also quotes the business-aviation desk NBAA Air Traffic Services at 3:49 p.m. Eastern (2049Z): "due to reported frequency and radar outages at several ARTCCs."

HEXBIRD's surface ADS-B shows what that looks like at O'Hare. These are airline aircraft transmitting on the ground within 4.5 km of the field, per half hour:

Airliners usually switch transponders off at the gate. Stationary aircraft still transmitting are mostly ones that pushed back or taxied out and are now holding on taxiways and pads. That count rose about sixfold.

How long? At O'Hare, 30 airline aircraft were transmitting on the field before 2100Z, were still there after 2310Z, and never went airborne. 15 of them were there before 2030Z. The same test finds 19 at Atlanta, 14 at LaGuardia, and 9 each at Charlotte and LAX.

The federal tarmac-delay rule gives airlines 3 hours on domestic flights, and 4 on international, to let passengers off or start a takeoff. Aircraft first seen before 2030Z hit 3 hours around 2330Z. Two caveats. ADS-B cannot tell whether passengers are on board. Some of these aircraft may have returned to a gate and kept their transponders on. Even so, the counts show where tarmac-delay pressure is building fastest: O'Hare, the first hub to stop, at 2016Z.

Video transcribed locally from the audio. YouTube's automatic captions were not used.

Two views of the same afternoon, built from every ADS-B position HEXBIRD received.

The emptying sky. Traffic over the lower 48 was flat until about 2015Z. It began falling before the national stop, as Chicago-area facilities went down and airlines held flights at the gate. After 2053Z departures from the 30 biggest airports went to almost zero. The sky has been draining ever since, as flights already airborne land and nothing replaces them. The red sliver at the right edge is the long-haul international releases that began at 2213Z.

Before and after. The same map at 2000Z, before the first trouble, and in the latest snapshot.

The SFO claim checks out. Earlier we declined to report a social-media claim that San Francisco was releasing Asia and Hawaii flights. The airport's own ATIS confirms it. Information N (2220Z) and O (2256Z), received by datalink, both read:

NATIONWIDE GROUND STOP EXCEPTIONS MEDEVAC HAWAII ASIA.

SFO's ATIS also says gate-hold procedures are in effect, with departures calling gate hold on 124.25 before pushback. ADS-B shows the exceptions in use. JAL 1 (777-300ER, to Tokyo) left at 2307Z, seven minutes after United 871.

Long-haul departures since 2302Z from the 30 monitored airports:

Domestic airline departures are still at zero. The only other climb-out was a Learjet charter from Midway.

Cause, as of 2313Z. The FAA still says only "temporary telecommunications outage". Some analysts now say FTI is the likely source. FTI is the FAA's telecom network, run by the contractor L3Harris, that carries radio, radar and data between FAA facilities. HEXBIRD has found no official confirmation that FTI or L3Harris is involved. News reports quote Homeland Security Secretary Mullin as saying a separate Microsoft outage today is not connected. That also disposes of the Chicago crew's 2102Z quip, "Microsoft, huh?"

United's ATC desk issued an update at 2240Z (relayed to crews from 2253Z) listing the first formal exceptions to Advisory 111:

NATIONWIDE DEPT STOP STILL IN EFFECT, TILL 0400Z FOR NOW PER
 ADVZY 111,*EXCEPTIONS BELOW*. MULTIPLE ATC FREQS STILL NOT WORKING.
 *INTL DEPTS: W.COAST TO HAWAII RLSD. EWR TO EUROPE RLSD W/MIT.
  U.S. TO PAC RLSD ONLY IF TRANSITING ZOA, ZAN (ANC) CENTER CLSD
  INTL ARVLS: HAWAII-W.COAST RLSD. MEXICO,CANADA,CARIB STILL
  INCL IN THE STOP. GUAM FLTS NOT STOPPED.*

In plain terms:

• West Coast–Hawaii flights may operate in both directions.
• Newark–Europe flights may depart with miles-in-trail spacing.
• Flights to the Pacific may depart only if routed through Oakland Center's oceanic airspace, because Anchorage Center (ZAN) is closed to them. This is the first report HEXBIRD has seen of a whole en route center being closed.
• Mexico, Canada and the Caribbean are still stopped.

ADS-B shows the releases happening. Since 2252Z:

These join the three Europe-bound releases from Boston and JFK at 2213–2231Z. Domestic departures are still stopped. Every airline aircraft that climbed out of the 30 mainland airports HEXBIRD monitors since 2250Z is a long-haul international flight. The memo's own words are "multiple ATC freqs still not working."

• ADS-B sweep of 30 mainland airports (2236–2252Z): no new airline departures. The only aircraft climbing near a hub was American 1024 at Orlando, and its track shows a go-around, not a departure. It descended to about 1,000 ft on approach, climbed back to 3,000 ft and is circling to try again.
• Calgary (CYYC) is now under a ground stop "until further advised", according to the 2200Z ATIS at Fort McMurray. The listed Canadian stops are now Toronto, Montréal and Calgary.
• American Airlines told a crew at 2227Z it is "NOT RELEASING ANY FLT PLANS UNTIL WE GET CONFIRMATION FROM ATC THAT FREQ ISSUE HAS BEEN RESOLVED. ALL FLIGHTS GROUND STOPPED UNTIL ATLEAST 2330Z … CANCELLATION PACKAGE GOING IN." This is the first sign in the datalink of an airline cancelling flights in bulk.
• Indianapolis ATIS (2154Z): "THERE IS NO UPDATE TIME AT THIS TIME."
• The FAA status feed at 2251Z dropped the per-airport departure-delay entries for Atlanta, O'Hare, Newark, JFK and Teterboro and kept only Houston Intercontinental. Those entries are estimates of delay, not the ground stop itself. With no departures in ADS-B, their removal does not mean those airports are departing again.

• Montréal–Trudeau (YUL) now has an FAA-listed ground stop program until 6:30 p.m. Eastern (2330Z), reason "other". Toronto Pearson's has been extended to 6:15 p.m. Eastern (2315Z). Canada's two largest eastern hubs are now holding inbound traffic.
• Alaska is departing. Like Honolulu, Anchorage kept launching flights within the state. Alaska 89 (737) climbed out at 2228Z and was at 29,000 ft heading south-southwest at 2239Z, and a Horizon flight followed at 2238Z. As with Hawaii, the stop is holding traffic bound for the lower 48, not flights that stay outside mainland en route airspace.
• Airborne aircraft over the contiguous US: 2,153 in the 2235Z bin, down 73% from early afternoon. The decline has slowed to about 100 aircraft per five minutes, from about 250 before 2200Z. That is what an emptying sky looks like when nothing new is taking off, not a sign of recovery.
• FAA status feed, 2240Z: departure delays are now 2 hours 16 minutes–2 hours 30 minutes at O'Hare and over 2 hours at Atlanta, Newark, Houston Intercontinental and Teterboro. JFK's delay is listed as decreasing. That is the first "decreasing" trend at a major airport since the stop began, but no departures from JFK other than ITA 609 appear in ADS-B yet.

A wider ADS-B sweep at 2235Z of 30 US airports, counting airline callsigns climbing out below 1,500 ft:

Honolulu (HNL) kept departing all afternoon. Its rate never dropped. The number of airline departures per half hour stayed between 3 and 12 from 1800Z through 2230Z, with 9 in 2200–2230Z. Since 2140Z:

• Japan: All Nippon 183 (A380) and Japan Airlines 799 (787) climbed out northwest and were at 36,000–37,000 ft by 2220Z.
• Interisland: a stream of Alaska-coded 717s (the former Hawaiian Airlines interisland fleet), Southwest 2032 to Maui, FedEx feeders and small commuter aircraft, heading to Maui, Kauai and the Big Island.
• Mainland: none. No departure from Honolulu toward the mainland appears. That fits United's note that flights from Hawaii to the mainland are "included in the stop". The stop is about aircraft entering mainland en route airspace. Flights that stay in Hawaii, or head west over the Pacific, never do.

JFK released a Europe flight. ITA Airways 609 (A330-900, to Rome) took off at about 2231Z, 18 minutes after the two Boston releases (Lufthansa 423 and ITA 615). Three transatlantic departures from two Northeast airports suggest the "case by case" Europe releases are now happening.

Nothing else at the large mainland airports. Apart from those three, no airline flight has climbed out of ATL, ORD, DFW, DEN, LAX, SFO, SEA, CLT, LAS, PHX, MCO, MIA, IAH, MSP, DTW, PHL, EWR, LGA, IAD, DCA, SLC, SAN, MDW, BWI, FLL, TPA or AUS since about 2105Z.

An ADS-B sweep of the 20 busiest US airports at 2230Z, counting aircraft climbing through 300–4,000 ft within 12 km of each airport:

Boston released two transatlantic flights. At about 2213Z Lufthansa 423 (A330) and ITA Airways 615 (A330), both bound for Europe, took off from Logan. By 2230Z they were at 18,000 and 10,500 ft, heading east over Massachusetts Bay. These are the first scheduled airline departures HEXBIRD has seen from a major US airport since about 2105Z. They match United's 2155Z note to crews that "Europe flights might be released soon on case by case basis".

Everywhere else, airline departures are still stopped. Last airline departure at each hub:

O'Hare stopped first, at 2016Z, more than half an hour before the national stop. What has left the hubs since then is medical transport, police and news helicopters, and light aircraft flying under visual rules, none of which this stop restricts.

On the claim that SFO is releasing Asia flights: a post circulating on social media says San Francisco cleared a Cathay Pacific flight to depart and then took it back. HEXBIRD cannot confirm what was said on frequency. In ADS-B, Cathay Pacific 879 (A350, to Hong Kong) taxied at up to 18 knots after 2130Z and is now stopped on the airfield. No flight has left SFO for Asia or Hawaii. EVA 7, China Airlines 5346 and JAL 57 are also sitting on the ground. Five minutes of live SFO tower audio at 2224Z carried only arrivals and runway crossings, with a United 777 told to "hold short of 28L for now". We will report any Pacific departure when it shows up in ADS-B.

Press reports quote a pilot saying the outage started at Kansas City Center. HEXBIRD pulled the archived Kansas City Center feed (LiveATC "ZKC-MCI") for 2000–2030Z, the half hour when Chicago's trouble began.

On this frequency Kansas City Center was working normally. Check-ins, descents and frequency changes were answered throughout, with no stuck mic and no unanswered calls. The controllers treated Chicago as the problem:

• 20:23Z. The controller to American 2720, which is heading toward Chicago: "unfortunately some bad news right now. [Chicago?] Center is [unclear] … I don't know [when] currently, but [it] will come back. So I recommend slow as practical, we'll keep you updated." The facility name and status are hard to make out. One model hears "Chicago Center"; another, run without hints, hears "cargo center".
• 20:27Z. The crew says its paperwork lists Grand Rapids as the alternate.
• 20:28Z. The crew asks: "how much further until we start hitting airspace issues?" The controller: "You've got 200 miles left … you're two sectors away from Chicago … just plan on it."

This is one feed covering a few Kansas City sectors. It does not rule out problems on other Kansas City frequencies or later in the afternoon. It does not support the claim that the outage started at Kansas City Center. Here, at 2020Z, Kansas City is a working center handing traffic toward a broken one.

Machine transcription; bracketed words are uncertain.

News 9 in Oklahoma City (2159Z) reports a National Weather Service notice of an outage affecting its online radar platform and web products: "You may not be able to access products on our webpages, or these products will be old." The article says "there is no confirmed connection" to the FAA ground stop. Some posts on social media have turned this into a "nationwide radar outage".

What HEXBIRD checked at 2217Z against the NWS's own data service:

• Radars: 157 of 159 WSR-88D sites report status "Operate", and one is starting up. Median data latency is under 1 second. The newest Level II data from almost every site is timestamped 2217Z.
• Forecast products: offices are issuing them normally. Products from San Francisco, Sacramento, Tallahassee, Seattle and others are stamped 2216–2217Z.
• Radar website: radar.weather.gov loads normally.

The weather radar network is running and its data is current. Whether the NWS websites had a separate access problem earlier today, HEXBIRD cannot confirm or rule out. @airplaneian says the notice circulating is an old one. News 9 presents it as current. Either way, it is a website matter. Nothing links it to the FAA's ATC radio outage, and FAA air traffic radar is a separate system from NWS weather radar.

Two tests of what the radio outage did to aircraft in the air, using every ADS-B position over the contiguous US since 1800Z.

1. Lost-comms squawk (7600). A crew that loses two-way radio contact is expected to set its transponder to 7600. From 2000Z to 2215Z, only two US aircraft did:

• N939ET, over north-central Tennessee at about FL170, 2038–2042Z
• N7144W, near Grand Rapids, Michigan, at 7,800 ft, 2122–2124Z

In the previous 24 hours there was one, in Texas. Two is a small rise, not a wave. Controllers kept nearly every flight in contact through backup frequencies, guard (121.5) and neighbouring sectors, as the audio shows, so crews never reached the point of declaring lost comms. N7144W was under Chicago Center, where the trouble began. N939ET, over Tennessee, was under Memphis or Indianapolis Center, so it extends the known footprint south.

2. Airborne holding. Advisory 116 warned of "nationwide airborne holding". We counted aircraft above 6,000 ft that turned more than one and a half full circles in a 15-minute window. That threshold also catches military training orbits, so the baseline is about 150 aircraft.

Holding did not surge. Allowing for the falling traffic, the share of circling aircraft stayed flat. The clusters that were airline holds, not military training, were:

• Northwest Indiana (about 41°N, 86°W), 2030–2100Z: 8 aircraft including American, Envoy, Frontier and NetJets flights, around FL200. These are O'Hare arrivals, matching the FYTTE holds heard on Chicago Center audio.
• The Philadelphia–New Jersey area (about 40°N, 75°W), 2045–2115Z: United and GoJet flights around 9,000–10,000 ft, consistent with Newark arrivals.

Most arrivals kept flowing without holding. The ground stop kept the system from filling up, so there was room to land what was already airborne.

The FAA status feed shows a ground stop program for Toronto Pearson (YYZ) from 2208Z to 2300Z (5:08–6:00 p.m. Eastern), reason "other".

The list of affected origins is wider than the US stop. It includes every US center: the lower 48 plus Anchorage (ZAN), Honolulu (ZHN) and San Juan (ZSU). It also names the Canadian control areas, from Vancouver (CZV) and Edmonton (CZE) to Montréal (CZU), Moncton (CZM) and Gander (CZQ), and Toronto's own area (CZY). In effect, nothing may take off for Pearson from anywhere in North America. Flights from the US were already held by Advisory 111. This program also stops domestic Canadian flights to Toronto, so its cause is at Toronto itself. HEXBIRD does not know what that is. One possibility is gate and ramp space, if aircraft bound for the US are sitting on Pearson's gates as they are at US stations. Nothing reviewed so far reports a Toronto equipment problem.

ADS-B around Pearson (aircraft between 500 and 6,000 ft within 30 km, per 15 minutes):

Departures from Pearson fell by more than half from 2015Z, about 40 minutes before the national stop was issued. That matches the timing of the first trouble at Chicago and New York, which together serve many Toronto routes. A few departures are still leaving, presumably domestic and overseas flights. Arrivals held steady until 2200Z. With the new stop, they should fall over the next hour as airborne flights land.

What the stop covers. Advisory 111 applies to US airports, but its effects reach both neighbours:

• Canada. Edmonton's arrival ATIS (2100Z and 2200Z): "GROUND STOP TO ALL UNITED STATES AND MEXICO LOCATIONS UNTIL 0400Z." Mexico is included because those routes cross US airspace. Kelowna's ATIS reports flow control at Vancouver and a Seattle ground stop. The FAA has a separate ground stop program for Toronto Pearson (from 2208Z to 2300Z, reason "other"). It covers inbound flights from every US center and from the Canadian control areas as well. HEXBIRD has seen no sign that NAV CANADA's own radios or centres have failed. No datalink message or ATIS mentions an outage there.
• Mexico. United's ATC desk lists Mexico among the international origins included in the stop. Anchorage's ATIS (2053Z) describes a "wide spread ground stop for all aircraft traveling over or to Canada and the contiguous United States." HEXBIRD has found no sign of a Mexican ATC outage. Mexico City's ATIS earlier in the day shows normal operations.

What ADS-B shows (distinct aircraft above 1,000 ft per 15 minutes):

Canadian traffic has barely moved. Domestic Canadian flying continues, and only flights to and from the US are held. Mexico's count began falling at 2115Z, consistent with US-bound departures being held and fewer flights arriving from the US. Receiver coverage over Mexico and northern Canada is thinner than over the US, so these counts show the trend rather than totals.

The New York Times live coverage quotes Homeland Security Secretary Markwayne Mullin as saying administration officials do not suspect foul play:

"There was no indication as of yet that this was a nefarious attack against us. It's just telecommunication outage as of right now."

This is the first on-record statement by a cabinet official on the cause. It matches the FAA's "temporary telecommunications outage" and the earlier law-enforcement comments reported in the press. "As of yet" and "as of right now" leave the question open.

The FAA's first public statement, posted on X at 2202Z:

"There has been a temporary telecommunications outage - out of an abundance of caution all flights have been halted. Every flight has been accounted for and international flights will be handled on a case by case basis."

What it adds to Secretary Duffy's 2116Z post:

• Category of failure: "telecommunications". This matches American's 2207Z message to crews. It fits the radio and frequency failures heard on ATC audio. Controllers' radios typically run over leased circuits to remote transmitter and receiver sites, so a telecom fault would take them down even with the radios themselves intact. The FAA has not said which circuits or carrier failed.
• "Temporary" signals that the FAA expects service back. It gives no time. Advisory 111 still runs to 0400Z.
• "Every flight has been accounted for" responds to concern about aircraft out of radio contact. It does not say how many flights lost contact or for how long.

Still not stated: the cause of the telecom failure, which facilities were affected, and whether radar was affected.

Distinct aircraft above 1,000 ft over the contiguous US, compared with the 1900–1930Z average of about 7,890:

The decline is still running at about 200 aircraft per five minutes. ADS-B shows no sign that departures have resumed. (The baseline is not adjusted for the normal evening drop.)

At 2211Z the FAA's NAS status feed carried a ground stop program for Toronto Pearson (YYZ) until 6 p.m. Eastern (2300Z), reason "other". It still lists no US national program. Departure delays have grown to 1 hour 31 minutes–1 hour 45 minutes at Atlanta and Fort Lauderdale, and JFK now shows an equipment delay ("EQ:OCL").

Analyst @airplaneian.com is knocking down two rumors circulating on social media:

• "Nationwide weather radar outage." The claim rests on an old notice on one National Weather Service forecast office's website. It concerned the website, not radar equipment. The Anchorage-area radar is up, and the NWS radar site shows no national outage. In his words: "this has nothing to do with enroute ATC, radio comms or radar."
• "A covered-up air defense incident." He reports that observed military traffic "has decreased in line with all airborne aircraft (~50% down baseline)" and that he checked TIS-B and MLAT data too: "Zero evidence of any kind of air defense or security incident."

HEXBIRD has not run a separate military-traffic count. Nothing in the datalink or audio reviewed so far points to a security incident. Earlier press reports cited law-enforcement sources saying preliminary indications are that this is not a cyberattack.

United's ATC desk sent this update to crews from 2155Z:

NATIONWIDE DEPT STOP STILL IN EFFECT, TILL 0400Z FOR NOW PER
 ADVZY 111, REGARDLESS OF DESTINATION. MULTIPLE ATC FREQS NOT
 WORKING. EVEN IF UR FLT OPERATES INTO ATC FACILITIES WITH
 WORKING FREQS, THEY ARE INCLUDED IN THIS STOP.
 AIRBORNE ACFT...ALLOWED TO CONTINUE FOR NOW BUT MIGHT HAVE TO
 DVRT AS SOME STATIONS ARE BECOMING CONGESTED ON GROUND.
 INTL DEPTS: U.S. TO INTL INCL IN THE STOP, BUT EUROPE FLTS
 MIGHT BE RLSD SOON ON CASE BY CASE BASIS.
 INTL ARVLS: HAWAII,CANADA,MEXICO,CARIBBEAN INCL IN THE STOP.
   GUAM DEPTS NOT INCLUDED.

The ground congestion is visible elsewhere. At 2200Z United's Austin station told an inbound crew: "WE ARE CRUNCHED FOR GATE SPACE. MAY HAVE TO HOLD, RAMP TOWING MULTIPLE PLANES OFF AND RAMP IS SWAMPED. SLOW DOWN IF POSSIBLE." At 2208Z a LATAM crew bound for Miami was asked whether it could still land there.

American's 2207Z message to all active flights calls it an "FAA TELECOMMUNICATIONS ISSUE". That is the first airline use of "telecommunications" HEXBIRD has seen. Earlier messages said "frequency" or "comms" issues.

These are airline relays of Command Center guidance, not the advisory text itself.

Spaceflight commentator Scott Manley suggested on X at 2153Z that the outage may be "limiting the ability for enroute centers to communicate with each other". When an aircraft is handed off from one center to the next, its flight data travels over a separate channel from the voice radio.

How that fits what HEXBIRD has heard:

• Against it as the whole story: the earliest audio shows air-to-ground radio failing. At 2006Z a pilot could transmit to Chicago Center but heard nothing back. Stuck mics were reported at 2012Z and 2118Z. Approach controls went "ATC zero", and New York was testing backup frequencies at 2107Z. A reply to Manley from an account that appears to work in ATC says the same: "outages in the terminal environment as well. Including frequencies, not just inter-facility coordination."
• Not ruled out: HEXBIRD has no direct view of center-to-center data links. A failure there could happen alongside the radio problems. In the 2100Z audio, Chicago controllers are still coordinating handoffs with neighbouring facilities ("I'm going to talk to C90"), at least by phone.

Earlier, at 2118Z, Manley asked: "So, does the FAA ground stop apply to rockets?" SpaceX was still counting down to a Starship launch this afternoon.

• CNN and Axios are running live coverage. Reporting cites FlightAware for nearly 7,000 delayed or cancelled flights.
• Global News and others cite law-enforcement sources saying preliminary indications are that this is not a cyberattack. HEXBIRD cannot evaluate that claim.
• One report quotes a pilot saying the outage started at Kansas City Center and spread. That is secondhand. It is consistent with the Chicago controller's 2102Z remark, "I think it's Kansas, New York," but the earliest trouble HEXBIRD has found in audio is still Chicago Center at about 2006Z. We have not checked any Kansas City Center feed.
• Some outlets report the stop lasting until 11 p.m. Eastern (0400Z). That is the end time written into Advisory 111, not a forecast of when flights resume.

• 11 September 2001. After the attacks, the FAA ordered every aircraft in US airspace to land and closed the airspace for days. That went much further than today's order, under which airborne flights continue.
• 11 January 2023. The NOTAM system, which carries the notices pilots must review before departure, failed overnight. The FAA stopped domestic departures for about 90 minutes that morning, lifting the stop shortly before 9 a.m. Eastern. The FAA later traced the failure to a contractor who deleted files by mistake while working on a database.
• 13 November 2026 (today). Advisory 111 stops all departures, not just domestic ones. As of 2208Z the stop has run about 75 minutes and the advisory is valid to 0400Z.

The 2023 stop was a pre-flight paperwork failure; ATC radios and radar kept working. Today's problem is in the systems controllers use to talk to aircraft in flight. Departures are being held so that fewer aircraft depend on those links.

Airline-requested ground stops of a single carrier's fleet, after IT failures, happen more often. They are not FAA national stops and are not counted here.

On the JFK-area feed, which mixes New York, Boston and Washington Center frequencies:

• 21:07Z. A New York controller to a JetBlue flight: "we're going to try our backup frequency … we'll do a couple checks, if you don't mind." The controller then calls "how do you hear New York?" three times over the next minute. The recording carries no clear reply.
• 21:18Z. A crew explains: "It sounds like there's a stuck mic on guard right now and another aircraft was asking if anyone could hear him."
• 21:24–21:27Z. A FlexJet crew and the controller exchange "5 by 5" and "loud and clear". The frequency is working by then.

This is the second report of a stuck mic; the first was on Chicago Center 120.225 at 2012Z. A stuck transmitter fits the symptoms pilots described, where crews could transmit but not hear replies. It is not established as the cause.

From the archived recording of Chicago Center sector 74 (FARMM), 2100–2130Z, just after the ground stop. This is the first audio that names which facilities were down.

• 21:02Z. A pilot asks if Chicago has an outage. The controller replies: "I don't know what's all out, but I guess like a nationwide outage. There's a lot of things out right now, so Rockford's ATC zero, Chicago Approach is limited there, Madison Approach, Milwaukee Approach, ATC zero as well." Asked whether it is local, he says: "I think it's Kansas, New York. I think it's all over."
• 21:03Z. "Another sector in Chicago Center is working Rockford Approach currently." This matches the Rockford NOTAM (2127Z entry).
• 21:11Z. "Pretty much all the approach controls in the surrounding area are ATC zero, Milwaukee approach as well."
• 21:24Z. "The Chicago Center area that's working all the Milwaukee arrivals … right now Milwaukee's a VFR tower only." Center gives VFR aircraft no flight following and reroutes IFR arrivals via the Dells and Oshkosh.
• 21:30Z. The sector covering Milwaukee is "not taking any more airplanes … everyone's holding up there just north of Milwaukee."

Two things go against a total collapse. O'Hare arrivals kept going to Chicago Approach on 135.02 throughout, and aircraft were handed to Madison Approach on 120.1 at 21:09 and 21:20, so Madison may have been back by then. The controller's "Kansas, New York" is hearsay on frequency.

The 21:02 clip ends with the crew's own diagnosis: "Microsoft, huh?" … "AI." … "That's just what we need." That is banter, not evidence.

Machine transcription, checked against a second model for the quoted lines. Callsigns and numbers may be misheard.

Transportation Secretary Sean Duffy posted on X at 2116Z:

"The @FAAnews issued a nationwide ground stop for all U.S. airports following a communication issue impacting all Air Route Traffic Control Centers. FAA technicians are investigating the issue."

This is the first official statement HEXBIRD has found. It says the problem reached all 20 en route centers, which is wider than the audio record shows. In the 2113–2124Z captures, sectors at Chicago, New York, Boston and Indianapolis Centers were working traffic normally, possibly on backup frequencies. It does not mention radar or give a cause. As of 2158Z the FAA's own account (@FAANews) has posted nothing about the outage.

At 2154Z the FAA's public NAS status feed listed no ground-stop program. The national stop shows up only as departure delays at individual airports, tagged with codes such as "NATIONAL STOP" (ATL), "NAS GS" (FLL, MIA), "STOP:EQ" (IAH) and "EQ:FAA" (EWR, ORD, TEB, LAS). Reported delays run from 16 minutes to 1 hour 45 minutes, and almost all are increasing.

An American crew at 2118Z had already told its dispatcher: "NASSTATUS ISNT SHOWING THAT." Anyone checking the public status page will see much less than the advisory says.

Distinct aircraft above 1,000 ft over the contiguous US, compared with the 1900–1930Z average (about 7,890):

The decline has held at roughly 250 aircraft per five minutes since 2100Z, with no sign of flattening. A flattening, or a rise in aircraft newly appearing at low altitude near major airports, would be the first ADS-B sign that departures had resumed. Neither has appeared as of 2150Z. Some of the decline is ordinary late-afternoon traffic. The baseline is not adjusted for time of day.

Aviation analyst @airplaneian.com published his own ADS-B count on Bluesky at 2115Z. Departures across the contiguous US fell from about 200 to about 60 per five minutes starting around 2035Z, roughly 20 minutes before the 2053Z advisory. The western US dropped first and hardest. That matches the timing in our own counts.

At 2147Z he wrote: "there is a communications outage affecting ARTCCs, the FAA is investigating and issued a ground stop for all departures." He pushed back on online speculation linking the outage to an AI-based traffic-management tool. Secretary Duffy promoted one, called "SMART", in September. He said a failure in a planning tool would not take down ATC radio or radar, and that there is "no evidence" of an attack. HEXBIRD has seen nothing in datalink or ATC audio that points to a cause.

• 2125Z, Frontier dispatch: "ATC GROUNDSTOP THROUGH 4Z BUT THAT FEELS VERY MUCH LIKE A PLACEHOLDER TO ME. ALLEGEDLY THERE WILL BE AN UPDATE AT 22Z."
• 2142Z, JetBlue dispatch: "NO CHANGES YET TO NATIONWIDE GROUNDSTOP. SOME PROGRESS TO RESTORING FREQUENCIES, BUT ATC COMMAND CENTER IS KEEPING GROUND STOP IN PLACE."
• 2146Z, Alaska dispatch: "CURRENTLY NO ETA WHEN THIS WILL BE LIFTED."
• Minneapolis departure ATIS Q (2053Z, still current at 2148Z): "GROUND STOP UPDATE 0400 ZULU."

Accounts of radar still conflict. United desks at 2133Z and 2140Z cite "COMMS + RADAR AT ENROUTE CENTERS" and "MULTIPLE RADARS". Delta's last update, at 2114Z, said no radar outages had been reported. All of these are airline relays, not FAA statements. An American dispatcher at 2124Z told a crew that international arrivals are also stopped. Advisory 111 says they are handled "case by case".

A NOTAM relayed by United dispatch at 2127Z:

SVC ROCKFORD APP CLSD FOR RFD. TERMINAL RADAR SERVICE AREA SER
INVOLVING VFR ACFT NOT AVBL. CTC CHICAGO ARTCC FOR TERMINAL RADAR
SERVICE AREA ARR COM

Rockford's approach control is closed and Chicago Center is handling its arrivals. Of the facilities named on frequency or in datalink so far, this is the first one confirmed by NOTAM.

The Kelowna (CYLW) arrival ATIS, issued at 2100Z, reads "FLO CTL AT VANCOUVER. GROUND STOP AT KSEA. DUE TO REDUCED SYS CAPACITY, ACFT MAY EXPERIENCE RSTRNS AND OR DLA." Canadian traffic bound for the US is being metered.

From 20:37Z, ZAU 74 (FARMM) holds an American flight at FYTTE ("expect further clearance at 2120"). From 20:39 to 20:53Z, the same sector clears holding aircraft for O'Hare on the FYTTE SEVEN arrival and hands them to Chicago Approach on 135.02. A SkyWest crew: "I'm out of the hold now." By 20:55Z, aircraft checking in on ZAU 62 report "loud and clear."

No ground-stop broadcast was heard on guard in the 2030Z or 2100Z recordings.

On the archived JFK-area feed, which mixes New York, Boston and Washington Center frequencies, a controller moves traffic at 20:27Z: "switch to my other frequency, 128.67." At 20:30:53, asked by a pilot whether to go back and report the old frequency working:

"I don't know what happened exactly, but we lost our frequency, but we got another one."

This is the first audio evidence of a frequency failure outside Chicago, about 25 minutes before the national ground stop.

• 20:20:42Z, ZAU 81 (CRIBB): the controller tells a training flight that the approach facility "lost their frequencies over there."
• 20:23Z, ZAU 92 (HAWKS high, 124.725): last transmission. The feed carries only one check-in before 21:30Z.
• 20:24Z, ZAU 74 (FARMM): the controller tells an Envoy flight: "unfortunately due to equipment issues over at the TRACON, I'm gonna have holding instructions for you … hold northwest as published, 10 mile legs, expect further clearance 2115."
• 20:27Z, CRIBB: "stand by, we're working on it, the approach lost their frequency, so I'm trying to coordinate."
• 20:30:44Z, Chicago Approach 119.0 (O'Hare final): last exchange, a United flight sent to the tower. The frequency is silent for the rest of the recording.

• 20:12Z, guard: two transmissions report that "someone on Chicago Center 120.225 has a stuck mic."
• 20:12–20:15Z, ZAU sector 62 (Harley): SkyWest 578A says "we hear that static, we thought there was a stuck mic… so we went back to departure." It calls repeatedly with no answer, ending "Center, SkyWest 578 Alpha, are you still there?"
• 20:15–20:19Z, ZAU 44 (Peotone): pilots report they can't get through on assigned frequencies.
• 20:16Z, guard: the controller answers SkyWest: "I can hear you on guard, just not on freq." The flight is then worked on 121.5.
• 20:19Z, ZAU 74 (FARMM): "We're getting a lot of interference on this one."
• 20:20Z, ZAU 44: a pilot checks in: "I understand you guys had an outage, so whatever it takes." Nothing intelligible follows on 120.125.

At 20:00:49 Chicago Center's CRIBB sector hands American 2774 to Chicago Center on 126.47. Six minutes later the crew calls on guard (121.5):

"American 2774 on guard, is anyone here? … We're trying 126.47, but sounds like we're getting through, but can't hear anything back."

The CRIBB controller replies "that's right frequency, 126.47, check your mic." At 20:09 the crew reports a second frequency also gave no reply: "somehow guard works perfect." This is the earliest sign of trouble found in any source. (Update, 14 Nov: all three frequencies in the earliest trouble reports HEXBIRD has found are served by a single remote radio site, the Jones RCAG in southwest Michigan. See the 0725Z entry.)

All audio entries are from archived public scanner recordings, transcribed by machine. Callsigns and numbers may be misheard.

Distinct aircraft above 1,000 ft over the contiguous US, as a percentage of the 1900–1930Z average:

The decline steepens at 2035–2040Z, about 15 minutes before Advisory 111 was published. That matches dispatchers holding flights at the gate from about 2041Z. With nothing departing, the curve is now mostly landings.

Captures 2122–2124Z:

The silent Cleveland sector is consistent with an outage, but could also be an empty sector or a receiver problem.

ATCSCC ADVZY 116 ALL/DCC 11/13/2026 NATION WIDE AIRBORNE HOLDING
EVENT TIME: 13/2100 - 14/0300
USERS CAN EXPECT AIRBORNE HOLDING TO ANY AND ALL AIRPORTS WITHIN THE
NAS DUE EQUIPTMENT OUTAGES. UPDATES WILL BE ISSUED AS ADITIONAL
INFORMATION BECOMES AVAILABLE.
132120-140330

Earlier, at 2053Z, a United flight from Austin was already holding at WELTS with an expect-further-clearance time of 2130Z. Its dispatcher asked whether it would be allowed into Chicago Center.

Two-minute captures of public live feeds, 2113–2116Z:

Light traffic is expected with departures stopped, so a quiet frequency does not by itself mean an outage. 33 other Center feeds would not connect during this check.

Delta dispatch update:

SEVERAL FACILITES HAVE FREQUENCIES
COMING BACK. SOME
FREQUENCIES STILL HAVING ISSUES. SOME
ARE COMBINING FREQS.
ISSUES TEND TO VARY. ZTL HAS WORK
AROUNDS IN PLACE.
COMMAND CENTER STILL TAKING INVENTORY
GROUND STOP ADVISORY ISSUED UNTIL 04Z
BUT ITS A FLUID SITUATION
STILL NO RADAR OUTAGES REPORTED

ZTL is Atlanta Center.

An Allegiant dispatcher to crews: "THERE ARE DEVELOPING ROLLING FREQUENCY OUTAGES HITTING ALL CENTERS." At 2055Z an aircraft weather and briefing feed carried "A NATIONWIDE GROUND STOP DUE TO FREQUENCY OUTAGES ACROSS ALL ARTCCS." Both are secondhand relays.

WORK AROUNDS ARE IN PLACE IN FACILITES
WITH FREQ ISSUES.
COMMAND CENTER TAKING INVENTORY.
FLTS ARE INBOUND TO JFK FROM ZDC AND
CHICAGO METROS ACCEPTING TRAFFIC
NO RADAR ISSUES REPROTED YET

Reports on radar disagree. Some dispatchers cite "radar and frequency issues". Delta's desk reports no radar outages. One Canadian carrier's reply says "Western US has a radar outage". None of these is an FAA statement.

The FAA Command Center advisory, as relayed verbatim by several airlines:

ATCSCC ADVZY 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.
132054-140430

Within minutes, ATIS broadcasts at Detroit, Tampa, San Francisco and Portland add the stop. Detroit's reads: "ALL DESTINATIONS IN USA ARE GROUND STOPPED DUE TO FREQUENCY ISSUES. NO DEPARTURES AUTHORIZED UNTIL FURTHER NOTICE."

United's ATC desk update, timed 2040Z and relayed to crews:

FREQ ISSUES AT MULTIPLE CENTER AND TRACON'S
- FAA NATION WIDE GROUND STOP BEING IMPLEMENTED DUE TO
  MULTIPLE FREQ ISSUES AT CENTERS AND TRACONS'S.
- IMPACTS TO FREQ'S AND RADAR CAPABILITIES.
- NATION WIDE GROUND STOP WILL BE ISSUED SHORTLY.

Between 2041Z and 2050Z, JetBlue, Allegiant, American, Delta, Southwest and Alaska dispatchers all send "do not push" messages. An Alaska SEA–EWR flight is told at 2052Z it may need to route around Chicago airspace.

A United dispatcher to a Chicago–Minneapolis flight: "ORD/MDW NATIONWIDE GROUND STOP DUE TO FREQ ISSUES, WILL ADVISE WHEN I HEAR MORE." This is the earliest datalink message found tying the stoppage to radio frequencies.

An American crew near O'Hare reports to its operations desk:

ATC JUST TOLD US
CHICAGO ATC ZERO. PULLED
BACK SPD. WHAT IS PREF
ALT OUTSIDE ORD ARSPC

ATC zero means a facility can no longer provide air traffic services, and traffic is held out of or routed around its airspace.

An American flight inbound to O'Hare asks its operations desk what is happening with Chicago Center:

KNOW ANYTHING ABOUT CHICAGO CENTER
HAD US SLOW

At 2025Z a United flight from Austin to O'Hare asks dispatch: "HEAR CHICAGO CENTER IS HAVING ISSUES… DO WE NEED TO CONSIDER AN ALT", naming St. Louis and Indianapolis as alternates.