FAA Outage Grounds US Flights Nationwide as Overloaded Routers Fail

The Federal Aviation Administration’s air traffic control communications network failed on Friday afternoon Eastern Time, and the FAA ordered a nationwide ground stop that kept departing flights at the gate across the United States, according to an official FAA notice reported by the Free Press Journal and The Times of India. The FAA later lifted the ground stop, but more than 4,000 flights had been cancelled and over 10,000 delayed, The Times of India reported.

The FAA said it imposed the halt “due to extraordinary circumstances and for reasons of safety.”

What broke at the FAA

The failure hit the telecommunications system that links the agency’s air traffic control centers. All 22 regional air route traffic control centers, which guide aircraft between airports across the country, were affected, The Times of India reported.

At a White House briefing, Transportation Secretary Sean Duffy blamed overloaded switches and routers in an ageing communications system. According to Duffy, the equipment was swamped with data and started sending inconsistent information, which caused intermittent communication and radar failures. He said the FAA shut the system down as a result. An airline source cited by CNN said the router problem spread nationwide and affected several facilities.

Before that explanation, Duffy wrote on X that FAA technicians were investigating.

Was it a cyberattack?

Officials said there was no sign of a deliberate attack. Homeland Security Secretary Markwayne Mullin told reporters outside the White House that preliminary assessments did not point to a threat to the United States, and that all flights had been accounted for. President Donald Trump said the outage was unlikely to have been caused by a cyberattack or artificial intelligence. Law enforcement sources told CNN that early reports indicated it was not a cyberattack, though investigators had not ruled anything out.

Mullin also rejected any link to a large Microsoft services outage earlier in the week.

Who was affected

The FAA advisory told airlines to keep all departing traffic on the ground until further notice and said inbound international flights would be handled case by case. Flights already in the air kept flying to their destinations.

• More than 4,000 flights cancelled and over 10,000 delayed in the US, according to The Times of India.
• An estimated 1.5 million passengers stranded, according to an analysis by data firm Cirium cited by CNN.
• United Airlines said its domestic flights would not depart during the stop, while the FAA managed its international departures case by case.
• American Airlines warned of disruptions for the rest of the day and said it would work to move customers once the stop was lifted.
• Air Canada said its flights between Canada, the Caribbean and South America that cross US airspace could be affected.

The FAA notification had set the ground stop to run until at least 11 p.m. ET on Friday. Before the FAA lifted it, an airline source told CNN that major carriers were considering shutting down operations for the evening.

Why it matters for travelers

This was the first nationwide ground stop since January 2023, when a malfunction in an FAA computer system disrupted flights across the country. Before that, the last one followed the attacks of September 11, 2001.

Lifting the ground stop did not clear the backlog right away: thousands of passengers were still dealing with cancelled and delayed trips afterward, The Times of India reported. Passengers were advised to check with their airline before heading to the airport.

What happens next

The FAA and other federal agencies continued to look into the cause and restore normal operations. Duffy warned that more outages would follow unless the air traffic control system is modernized, and he urged Congress to pass legislation funding the upgrade.

Sources: Free Press Journal, The Times of India