'The line-up is huge': Australians caught up in US flight chaos

Adelaide woman Trish Crabb is stranded at JFK Airport in New York after thousands of flights were cancelled and delayed. ( Supplied: Trish Crabb )

A major air traffic control outage in the US has disrupted thousands of flights, leaving Australians stranded and warnings about global flow-on impacts, including international delays.

Airlines are working to clear the backlog as US authorities investigate what caused the outage.

Australians have been caught up in widespread flight disruptions across the United States after a communications outage forced aviation authorities to ground flights nationwide.

More than 11,000 flights were delayed or cancelled, with passengers left stranded at airports across the country after the Federal Aviation Administration (FAA) issued an unprecedented ground stop.

The grounding has since been lifted, but airlines are warning it could take time to clear the backlog, with disruptions also affecting flights departing Australia for the US.

Sydney Airport said flights to the US would now resume from Mascot after being temporarily grounded on Saturday morning, and urged passengers to contact their airlines.

The disruption has affected travellers at major airports including New York's JFK, Los Angeles International Airport and San Diego.

Copyright for this text belongs to ABC Australia.