On November 13 at approximately 3:30 p.m. ET, the FAA experienced a technical problem that resulted in issuing a nationwide ground stop.

The ground stop was issued out of an abundance of caution. Safety is, and will always remain, the FAA’s highest priority. We will never compromise the safety of the flying public.

The system was made stable and air traffic resumed as of 8:15 p.m. that same day. Recovery to normal operations will be slow and steady. We ask for your patience as airlines work to get you to your destination. 

Check your flight status and get real-time airport updates at nasstatus.faa.gov.
 

Questions and Answers

Q: What caused the outage?
A:  Americans’ safety is always our top priority. Out of an abundance of caution, the FAA implemented a nationwide ground stop to ensure aircraft could continue to operate safely.  
The FAA’s legacy equipment became unstable when data began flooding the FAA FTI network, at a rate of 1,000 connection attempts every 4 to 5 seconds. This disrupted the system and created instability with aircraft communications and radar feeds.

The initial investigation indicates that two potential locations as the reason for the excessive data flooding the systems: a radar site in Amarillo, Texas and a radio communications site in El Dorado, Arkansas. L3 Harris, the FAA’s current network service provider, had been doing work at the El Dorado site, including deployment of a new router. When these inconsistencies in the data happened, L3 Harris blocked those two locations and the network stabilized. The broadcasting function was also disabled on all the new routers as a precaution.

We worked as quickly as possible to identify, isolate and address the cause. Because the flying public’s safety is our top priority, we waited for a period of time to ensure the system was stable before we lifted the ground stop and allowed flights to resume. The system is stable, and operations are returning to normal. The FAA and L3Harris continue to investigate the root cause and ensure this doesn’t happen again.

Q: Was safety compromised?
A: No. The FAA has clear, established, standard procedures to ensure safety during incidents such as this. Throughout the disruption, certain radio frequencies and radar feeds remained operational, allowing air traffic controllers to maintain communication with and track aircraft. Our highly trained air traffic controllers and pilots continued to follow established safety protocols, and we implemented a nationwide ground stop out of an abundance of caution. As a result, every aircraft landed safely, and all passengers arrived safely.

Q: Is it safe to fly?
A: Yes. The United States has the safest aviation system in the world, and the safety of the American flying public is, and always will be, the FAA’s top priority.

Q: How many facilities were affected?
A: We began experiencing instability at 17 of our 22 Air Route Traffic Control Centers, and it spread into several Terminal Radar Approach Controls. Out of an abundance of caution, we implemented a nationwide ground stop to ensure the safety of the flying public.

Q: Was this a cyberattack?
A: Based on all available evidence, we have no indication that this was a cyberattack or an outside nefarious actor.

Q: Did your upgrades and modernization efforts cause this?
A: No, this is due to the legacy TDM system causing instabilities. None of the upgraded towers that received modifications from the down payment in the Working Families Tax Cuts went down. This type of work has been going on for years to transition from old copper wires that are being disconnected due to their obsolescence. It is important to distinguish routine equipment upgrades from the FAA’s broader modernization effort.

Q: Was this caused by SMART system?
A: No. The two systems are not related. SMART is a data aggregator, and it does not feed information into the air traffic control system.

Q: How many flights were in the air when the FAA implemented the ground stop?
A: Approximately 3,500 aircraft safely landed, and every passenger arrived safely. Credit goes to our highly trained pilots and air traffic controllers, whose professionalism and expertise ensured the safe operation of aircraft throughout the national airspace system.

Q: Did critical operations continue? 
A: Yes. Throughout the ground stop, frequencies remained available to safely land commercial aircraft and ensure that critical life-saving, law enforcement and military flights continued. There were no impacts to critical operation flights.

Q: Did you lose radio and radar communications with aircraft?
A: No, this was not a full outage. Some frequencies and radar feeds remained reliable. 

Q: What backup capabilities were available to support the system during disruptions?
A: The FAA’s telecommunications system remained operational but experienced instability. The existing safety protocols in place worked: we took immediate action, safely implemented the ground stop out of an abundance of caution, and ensured every flight landed safely.

We are investigating the system inconsistencies in the network operated by L3 Harris. This underscores the importance of modernizing our aging infrastructure and secure state-of-the-art, 21st century system that meets the demands of today’s aviation system.

Q: How many flights were cancelled?
A: On Friday, Nov. 13, following a telecommunications failure that prompted a nationwide ground stop, operators canceled approximately 12,462 flights, including 9,082 cancellations by major airlines, out of an abundance of caution. While not all cancellations were directly caused by the nationwide ground stop, all flights landed safely. Airlines are working to restore normal operations from the temporary disruptions and return to normal operations.  

Q: How long will it take operations to return to normal?
A: The system is stable and operations are returning to normal. Planes are pushing back, taxiing, and taking off, and it is safe to fly. We are in close coordination with the airlines to support the ongoing recovery.

Q: Why was the router replacement work done in the middle of the day and not at night?
A: Maintenance at major air traffic control facilities is typically conducted at night, when there’s less traffic. This disruption was a result of a routine replacement at a remote facility, which has regularly been done for decades, without any impacts to the systems at these times. However, based on what happened Friday, we will reevaluate when we do replacement/maintenance work.

Q: What measures were taken to ensure the issue was fully resolved before resuming normal operations?
A: We always prioritize Americans’ safety above all else. When we were alerted of the inconsistencies, we worked as quickly as possible to identify, isolate and address the cause. Because the flying public’s safety is our top priority, we waited for a period of time to ensure the system was stable before we lifted the ground stop and allowed flights to resume.

Q: How will the FAA prevent a recurrence?
A: We believe we have addressed the initial cause of the disruption by immediately disabling the functionality of the originating routers. As a precaution, we disabled the same functionality on approximately 60 similar routers in the system.