Air traffic control failures on both sides of the Atlantic have caused widespread flight disruption, highlighting the consequences when critical aviation infrastructure loses the communications and data systems on which controllers depend.
In the United States, hundreds of flights were cancelled and thousands delayed Monday, September 21, after communications problems at a Federal Aviation Administration facility in Philadelphia disrupted operations across the Northeast.
The facility’s primary communications circuit failed and, when the system attempted to switch to its backup, officials discovered that the backup fiber-optic line had been accidentally severed during railroad construction. Controllers were left without radar and communications for hours. More than 600 flights into and out of Newark Liberty International Airport were cancelled, while Philadelphia, JFK and LaGuardia also experienced significant disruption. Operations largely resumed Monday evening, although delays and cancellations continued Tuesday.
The U.S. breakdown came the same day as another air traffic control failure in the United Kingdom.
NATS, Britain’s air navigation service provider, reported a connectivity problem at its Prestwick control center in Scotland on September 21. Traffic restrictions were imposed while engineers investigated, affecting airports including Manchester, Glasgow and Belfast. NATS said the problem was confined to part of its systems network supporting Scottish operations and was subsequently repaired.
The timing was particularly notable because the Prestwick failure occurred less than two weeks after a separate major NATS outage on September 8. That incident resulted in roughly 2,000 flight cancellations and disrupted hundreds of thousands of passengers.
NATS traced the September 8 failure to a software defect in part of its National Airspace System flight-data system. The defect corrupted flight-data updates, forcing restrictions across UK airspace while the system was restarted. NATS said the September 21 connectivity problem was unrelated.
Although there is no indication that the U.S. and UK incidents were connected or malicious, the succession of failures is focusing attention on the resilience and redundancy of systems that underpin modern air travel. Airlines have been particularly critical in the UK, with easyJet saying the latest incident again raised questions about the resilience of NATS systems.
The incidents demonstrate how a localized communications, connectivity or software failure can rapidly become a national—and even international—transportation problem.