FAA lifts ground stop on US flights after nationwide system failure; normal air traffic resumes

The Federal Aviation Administration has lifted the ground stop on all U.S. flights after a nationwide system failure. 

The FAA said in its latest update that "normal air traffic operations are resuming gradually across the United States following an overnight outage to the FAA’s Notice to Air Missions (NOTAM) system that provides safety information to flight crews. The ground stop has been lifted."

"The agency continues to look into the cause of the initial problem."

The FAA said that the NOTAM system (Notice Air Missions) operated by the FAA failed down on Wednesday.

As flights gradually resume, airlines are advising passengers to check their status beforehand.

United Airlines: "Customers may continue to see some delays and cancellations as we work to restore our schedule and should check the United app or united.com for the latest information about their individual flight. United has activated a travel waiver for any customers who need to change their plans, including offering refunds for customers who no longer want to travel."

RELATED: FAA nationwide system outage impacting flights at Orlando International Airport

Southwest: "The FAA has notified airlines that the Notice to Air Missions (NOTAM) system is not functioning, and a nationwide ground stop of air traffic is in effect. As a result, Southwest anticipates some schedule adjustments as we await resolution of the issue by the FAA and a lifting of the ground stop."

White House Press Secretary Karine Jean-Pierre said President Joe Biden has been briefed by the Secretary of Transportation on the FAA system outage. 

"There is no evidence of a cyberattack at this point, but the President directed DOT to conduct a full investigation into the causes," she tweeted.

The president spoke briefly with reporters saying the FAA doesn't know yet what caused this, but they are working on it. 

"Aircraft can still land safely, they just can't take off right now," he said.

Frustrated passengers across the country tweeted on Wednesday that their flights had been grounded. 

"Flights delayed leaving Tampa International this morning due to #FAA computer glitch per @SouthwestAir." – @beavis38ghz

"Communication Systems are down US wide for the FAA? What in the world #FAA." – @GhoulyJules

"Stuck on SFO tarmac for an hour now. Nationwide plane grounding because #FAA computers are down. Pilot says in 29 years he’s never heard of this." – @austinandlynnz

"Flight delayed already...uuugh the #FAA apparently has systems down and no flights can take off rn? #MiamiInternational sounds sus to me!" – @suggamonkeybae

"#FAA system down nationwide - all flights are grounded indefinitely. Unfortunately that includes mine @united." – @aclegg09

"Anyone one else stranded? Our @united (pilot) says there is a nationwide outage of FAA @FAANews computer systems." – @dpatil

This is a developing breaking news story. Check back for details.