American Airlines has resumed flights after suspending its services for around an hour on Tuesday due to a technical issue that impacted the systems needed to release its planes.
The nationwide halt was cancelled just before 13:00 GMT, according to the Federal Aviation Administration (FAA).
The disruption came during one of the busiest travel days of the year as passengers made journeys on Christmas Eve.
In a statement, the airline said a “vendor technology issue” had caused the issue and it was “all hands on deck” to minimise further disruption.
“We sincerely apologise to our customers for the inconvenience this morning,” the airline said.
“It’s all hands on deck as our team is working diligently to get customers where they need to go as quickly as possible.”
Departure boards at major US airports are still showing delays of up to two hours for some flights as the airline recovers from the nationwide issue, but real-time tracking website Flightradar24 shows planes taking off again at a number of major US travel hubs and most flights are departing on time.
Passengers reported on social media being stuck on the tarmac or at gates as flights were impacted by the outage for around an hour.
Some passengers were also told to disembark from their planes.
In a video posted on X by a CBS reporter in Fort Lauderdale, Florida, a gate agent announced a flight to Philadelphia was going to start boarding.
“The system is slowly coming back,” the agent announced from a gate.
In July, American Airlines, among other major operators, grounded flights across the US due to communication issues caused by a global IT crash.
That failure – which also affected banks and emergency services – was caused by a faulty software update from cybersecurity firm Crowdstrike.