Airport operations across the US north-east resumed Monday evening after a communications line failure snarled flights at some of the country’s busiest airports, leading to thousands of flight cancellations and delays.
Flights were halted at several airports after a primary communications line failed at a key Federal Aviation Administration (FAA) facility in Philadelphia. The backup fiber optic line, which delivers internet service, was inadvertently severed by a railroad construction crew, resulting in a telecommunications crash and hundreds of canceled flights at Newark, LaGuardia, JFK, Philadelphia and Boston airports.
Transportation secretary Sean Duffy said in a Monday evening social media post that the backup lines had been fixed and all affected airports were again operating.
“It will take some time to clear all existing delays, so please check with your airline for the latest information,” Duffy wrote.
The technical problems stem from the same FAA facility in Philadelphia that caused numerous disruptions at Newark Liberty international airport in the spring of 2025.
Regional control centers like these have two lines that carry radar and communications data in and out: the primary and the backup. The FAA said a circuit on the primary failed Monday morning, and when the system tried to switch to the backup, workers discovered that the fiber optic line had been cut.
Earlier in the day, Duffy said an Amtrak construction crew was to blame. Amtrak, however, pointed to a New Jersey Transit construction crew that was working in the area between Newark and New Brunswick, New Jersey.
The disruption coincided with the publication of a government accountability office (GAO) report, which found that the FAA has yet to finish risk assessments or update security documentation covering threats from spoofing, jamming and other attacks on the radio spectrum – prompting a prominent senator to warn of a “major threat” to national security.
The FAA also lacks a real-time system to detect all such threats, the report said, meaning it can generally only investigate incidents after they are reported.
Investigators warned that a hacker could send fraudulent messages, such as false cancellations of flight clearances, to aircraft, with the potential to cause delays, disrupt airspace or create safety risks. Two systems used to send text messages to aircraft predate modern cybersecurity standards and lack common protections such as encryption, according to the report.
The watchdog’s findings prompted calls for swift action. “The FAA’s failure to require the aviation industry to use secure communications is a major threat to US national security, to our economy and the safety of the flying public,” said Ron Wyden, the US senator for Oregon, who has long campaigned on privacy, surveillance and cybersecurity issues.
“The FAA needs to issue new standards, as soon as possible, to protect the security of airline communications.”
The GAO made nine recommendations, including a formal risk assessment of seven of eight reviewed systems, continuous monitoring for interference, spoofing and jamming, and formal guidance on information sharing. The Department of Transportation, replying for the FAA, agreed with all nine.
Monday’s disruption is the latest in a run of problems around Newark. In April 2025, an outage blanked controllers’ screens for roughly 60 to 90 seconds and cut their contact with aircraft, prompting the FAA to halt departures. The FAA later moved the Philadelphia Tracon to a new fiber-optic link with New York on two separate paths, as part of measures to improve reliability.
The FAA handles more than 44,000 flights a day and about 3 million passengers, the GAO noted.
Wyden, who sits on the Senate intelligence committee, added: “This sobering report from [the] GAO reveals that the technology used by air traffic controllers to communicate with aircraft is incredibly insecure, can be intercepted, impersonated, and jammed, and that hackers and foreign governments can exploit these vulnerabilities to disrupt air travel and even put passengers at risk.”
The GAO also pointed to jamming and spoofing abroad. Estonia and Finland have accused Russia of interfering with satellite navigation in their airspace, which Moscow denies.
One incident last September involved a Spanish military jet carrying the country’s defense minister.
The Associated Press contributed
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