A nationwide ground stop across the United States that resulted in thousands of cancelled flights originated from complications following a copper wire upgrade, according to Transport Secretary Sean Duffy. Speaking at a press conference, Duffy stated that authorities are investigating whether the malfunction stemmed from faulty hardware or human error by the contractor responsible for the modernization.
Duffy noted that while investigations remain ongoing, federal officials currently have no indication that a cyber-attack was involved. The flight suspension on Friday marked the most extended incident of its kind since the September 11, 2001 terrorist attacks, with travel disruptions anticipated to persist for multiple days.
The work involved transitioning from copper cabling to fiber optics, executed by the technology vendor L3Harris, as Duffy pointed out. He further remarked that the United States operates with an exceptionally antiquated telecommunications network, noting that the specific wire being replaced was so outdated that production had ceased.
According to the transport secretary, a router undergoing maintenance began overwhelming other air traffic control networks and generated aircraft communication failures, prompting the administration to close the airspace as a precautionary measure.
Federal Aviation Administration chief Bryan Bedford stated during the briefing that there is no indication of malicious activity or artificial intelligence involvement.
Following the directive, departures from the continental United States were halted for over four hours beginning at 15:54 EST on Friday. Data from the tracking platform Flight Aware showed that cascading disruptions led to more than 3,500 flight cancellations and over 2,000 delays nationwide on Saturday. Certain travelers remained trapped inside aircraft on the tarmac without the ability to depart or return to terminal gates, while select international departures were permitted to leave in order to alleviate congestion.
Duffy cautioned that comparable failures could recur unless the US Congress authorizes funding to modernize air traffic control systems. President Donald Trump has asked for $30.1 billion for these improvements, with the Republican Party holding majorities in both congressional chambers.
Former Transportation Security Administration head John Pistole remarked to the BBC that restoring operations within four and a half hours demonstrated system resilience, though he questioned the guarantee against future occurrences. A complete national ground stop has previously occurred only once since all departures were prohibited for multiple days following the September 11 attacks.