American Airlines apologises after US flights grounded earlier due to 'technical issue'

American Airlines has apologised after all its US flights were briefly grounded on Christmas Eve due to a systemwide technical issue.

The US airline has resumed all of its flights after it was cleared to fly by regulators about an hour after a national ground stop order was issued, halting all American Airline flights across the world.

In a social media post to frustrated travellers, the airline said: "We have resolved a vendor technology issue that briefly affected flights this morning.

"We sincerely apologize to our customers for the inconvenience and have issued a travel alert to allow for additional flexibility."

There were 1,447 delays for flights entering or leaving the U.S. early in the day, with 28 cancellations.

The groundings couldn't come at a worse time for the millions of travellers expected to fly over the next 10 days.

The Transportation Security Administration expects to screen 40 million passengers over the holidays and through January 2.

The airline said in an email that the problem Tuesday morning was caused by a vendor technology issue that “impacted systems needed to release flights.”

Many flights during the holidays are sold out, which makes cancellations more disruptive than during slower periods so just a brief outage can have consequences days later. A post on the Federal Aviation Administration's website earlier acknowledged the airline's request for a “nationwide groundstop” for all American Airlines planes and their subsidiary airlines.

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