The telecommunications network upgrade caused a massive disruption to the US air traffic control system: on Friday, November 13, the FAA suspended flights across the country for about five hours. There were interruptions in the transmission of radar data and communication with aircraft. The aircraft already in the air continued their flight and landed safely.
Image source: Nils Huenerfuerst/unsplash.com
During the day, about 4 thousand flights were canceled and approximately 10 thousand were delayed. The ban on flights has already been lifted, but restoring the schedule will take additional time: airlines will have to redistribute planes and crews.
According to preliminary data, the problem arose when updating a closed telecommunications network connecting FAA facilities. Sources told CBS News that the update caused a reboot, followed by a system crash and communication outages. This is still a preliminary explanation and not the final results of a technical investigation.
US Transportation Secretary Sean Duffy blamed the failure on legacy switches and routers being overloaded. According to him, control centers began to receive inconsistent radar data, and there were interruptions in communication with aircraft. To restore operation, specialists made corrections that reduced the load on network equipment. The FAA tested the systems’ functionality before resuming flights.
Thus, we are not talking about a failure of computers on board aircraft, but about a failure of the ground network through which the data needed by dispatchers is transmitted. At the same time, according to Duffy, the new equipment continued to work – the old sections of the infrastructure failed.
A significant part of this infrastructure uses TDM – time division technology. It allows you to transmit multiple data streams over one line, allocating each its own time slots. The FAA is gradually transitioning such connections to modern IP-based networks. The problem is not in the principle of TDM itself, but in aging equipment and the curtailment of support for corresponding services by telecom operators. The FAA noted the need for the transition back in 2019 documents.
US Secretary of Homeland Security Markwayne Mullin said that, according to preliminary assessments, the introduction of new equipment and technology has overloaded the old system. He also said that the incident was not related to a global Microsoft outage. The authorities did not find any signs of a cyber attack, although Mullin responded to subsequent clarifying questions that the investigation was ongoing and it was too early to completely rule out any versions.
Duffy called on Congress to allocate more money to modernize air traffic control and warned that he could not guarantee that there would be no further disruptions. According to Mullin, a complete update of the system will require about $50 billion: spot improvements, in his opinion, no longer solve the accumulated problems.
The previous nationwide flight suspension occurred in January 2023. Then another FAA system, NOTAM, which distributes operational notices important to pilots, failed. It was specifically about stopping flights, and not ground handling of aircraft.
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