Federal aviation officials were warned repeatedly, in government reports issued over the months and years before last Friday's nationwide shutdown, that modernising the air traffic control network could disrupt flights, the Washington Post reported on Saturday. The new account of the FAA ground stop warnings adds a troubling history to the longest nationwide ground stop since September 11, 2001: the same contractor's predecessor caused a remarkably similar failure in November 2009, when maintenance errors blocked flight-plan data and delayed more than 800 flights. Investigators still have not established whether Friday's failure was an installer's error or a defective router, after a stoppage of 4 hours 21 minutes that delayed or cancelled more than 15,000 flights and affected about 1.5 million passengers.

Key Points

• The Washington Post reported on Saturday, November 14, 2026, that the FAA received repeated warnings in government reports, over months and years, that modernising the air traffic control network could disrupt operations.
• The warnings put the copper-to-fibre transition under scrutiny as investigators work to establish what went wrong on Friday, November 13.
• In November 2009, the same contractor's predecessor, Harris Corporation, caused a similar failure on the FAA Telecommunications Infrastructure network, blocking flight-plan data and delaying more than 800 flights.
• A June 17, 2010, investigation by the Department of Transportation's inspector general found contractor maintenance errors and said FAA oversight could have been more proactive.
• Friday's ground stop lasted 4 hours 21 minutes, hit 17 of 22 en route centres and delayed or cancelled over 15,000 flights; no cyberattack or AI evidence was found.

What Happened

The Post's report, published on Saturday, says government reports had outlined the risks in the months and years before the shutdown, putting the transition from ageing equipment to newer systems under scrutiny. The disruption began while contractor L3Harris was updating telecommunications infrastructure at a remote location, Transportation Secretary Sean Duffy said on Saturday, replacing copper connections with fibre optics. A router being replaced flooded other routers with more than 1,000 connection attempts every four to five seconds, hitting 17 of the FAA's 22 en route centres.

The FAA lifted the ground stop on Friday evening after testing its systems for stability and reliability, according to the Associated Press. The order restricted departing aircraft, though hundreds of flights were diverted. Airlines kept dealing with cancellations and delays on Saturday, and FAA Administrator Bryan Bedford said scheduling problems were expected to be resolved by Sunday evening, a forecast rather than a confirmation of normal operations.

Background: The 2009 Failure

The 2009 precedent is strikingly close to Friday's events. In November 2009, maintenance errors on the FAA Telecommunications Infrastructure network, which carries flight-plan data between air traffic control facilities, blocked flight-plan data and delayed hundreds of flights. The failure was traced to faulty router configurations, inadequate verification and monitoring failures, the same kind of work now at the centre of the 2026 investigation.

A June 17, 2010, investigation by the Department of Transportation's inspector general found contractor maintenance errors had caused the outage and said FAA oversight could have been more proactive. Harris Corporation, the contractor behind that failure, merged with L3 Technologies in 2019 to form L3Harris, the FAA's legacy network provider for more than 20 years. The parallel is now central to the questions facing the agency: whether the lessons of 2009 were learned, and whether the oversight the inspector general called for was ever put in place.

FAA Ground Stop Warnings Put the Copper-to-Fibre Upgrade Under Scrutiny

The modernisation programme at the heart of the warnings is vast. Congress approved $12.5 billion in July 2025 to modernise the ageing air traffic control system, and Duffy has asked for $50 billion to complete the job. L3Harris says it has completed more than 70 percent of its copper-to-fibre conversions, according to NPR, and is supporting the FAA's investigation.

The Post's account of earlier warnings raises questions about how those transition risks were managed, but it does not by itself establish the technical cause of Friday's outage. The investigation must now distinguish the limitations of older equipment from any failures in installing and testing its replacements, and whether the warnings issued over the years were acted on, filed away, or never reached the people doing the work.

Reactions and Quotes

Duffy said on Saturday that investigators were examining whether an installation mistake or a faulty router triggered the problem, and that the precise error, and whether L3Harris was responsible, had not been established at that briefing. L3Harris said it was supporting the FAA's investigation; the company has not been found responsible for Friday's failure.

The FAA said it tested its systems before allowing departures to resume. Officials have found zero evidence of a cyberattack or AI involvement, a point the agency has stressed as speculation about the cause circulated online.

Why It Matters

The stoppage was the longest nationwide ground stop since September 11, 2001, and its scale, 17 of 22 en route centres, more than 15,000 flights delayed or cancelled, about 1.5 million passengers affected, shows how a single point of failure can paralyse the whole system. The warnings matter because they suggest the risk was known: Duffy had already blamed L3Harris contractor work and a faulty router, and the chaos dragged into Sunday with more than 6,150 flights cancelled, after the original four-hour nationwide halt. government reports had flagged the danger of disrupting operations during modernisation, and a near-identical failure had already happened in 2009. If the warnings were not acted on, the question is not only what went wrong on Friday, but why a known risk became a national shutdown, and what that means for a modernisation programme with years of work still ahead.

What Happens Next

The investigation continues, with the central question still open: whether Friday's failure was an installer's error or a defective router. Duffy used Saturday's briefing to call for further investment, pressing his case for $50 billion. Congress, which approved $12.5 billion for modernisation in July 2025, is likely to examine both the warnings and the 2009 precedent as it weighs that request. For passengers, the immediate disruption is easing, but the deeper test, whether the network can be modernised without another stoppage, is only beginning.

Frequently Asked Questions

What did the Washington Post report?
The Post reported that the FAA received repeated warnings in government reports, over months and years, that modernising the air traffic control network could disrupt operations.

What happened in the 2009 failure?
Harris Corporation maintenance errors blocked flight-plan data and delayed more than 800 flights; a June 17, 2010, inspector general investigation blamed contractor errors and said FAA oversight could have been more proactive.

How long was Friday's ground stop?
It lasted 4 hours 21 minutes, from 3:54 p.m. to 8:15 p.m. ET on Friday, November 13, 2026, the longest nationwide stop since September 11, 2001.

How many flights were affected?
More than 15,000 flights were delayed or cancelled, about 1.5 million passengers were affected, and 17 of the FAA's 22 en route centres were hit.

Was it a cyberattack?
Officials have found zero evidence of a cyberattack or AI involvement; whether it was an installer's error or a defective router is still undetermined.