London: Britain's Heathrow Airport and Irish no-frills airline Ryanair warned Friday that they faced turbulence over spreading travel chaos emanating from a global IT outage.

Heathrow warned the issue was affecting some systems while Ryanair admitted it faced disruption over a "global third party outage" but both insisted flights remained operational.

"Microsoft is currently experiencing a global outage which is impacting select systems at Heathrow," the airport posted on X.

"Flights are operational and we are implementing contingency plans to minimise any impact on journeys. Please check with your airline for the latest flight information."

Dublin-based Ryanair warned it faced fallout from the meltdown which sparked technical issues worldwide -- including at Britain's Sky News TV channel and the London Stock Exchange, as well as railway operators and GP surgeries.

"We're currently experiencing disruption across the network due to a global third party IT outage which is out of our control," Ryanair said in a statement on X.

"We advise all passengers to arrive at the airport at least three hours before their scheduled departure time."

Dublin Airport added that its staff were on hand to assist affected Ryanair passengers. Meanwhile American Airlines says resumed operations after global IT outage

Washington, United States American Airlines said Friday it had resumed operations following problems linked with a major worldwide computer systems outage.

"Earlier this morning, a technical issue with a vendor impacted multiple carriers, including American. As of 5:00 a.m. ET (0900 GMT), we have been able to safely re-establish our operation," it announced in a post on social platform X.  -AFP