Travellers have been facing widespread disruption with cancelled flights and airports suffering system failures globally.
The IT failure has stretched right around the world with airports and airlines impacted from the US to New Zealand.
Cybersecurity firm Crowdstrike, which has thousands of business customers globally, said a defective software update has caused the major global outage.
It impacted Ryanair’s app and website, while airports reported various IT issues, at Berlin Brandenberg, Amsterdam Schiphol and Zurich.
Airports in New Zealand, Japan, and India also faced disruption.
In the UK, London Heathrow, Gatwick, Manchester, Stansted, and Luton have been experiencing outages.
In the US the big three airlines American Airlines, Delta and United Airlines issued ground stops early on Friday.
Today is the expected to be the busiest day so far this year for UK departures.
The outage has also affected trains, medical clinics and supermarkets.
Sky TV also went off the air as a result of the outage.
George Kurtz, CEO of Crowdstrike, confirmed it was a defective software update.
It seems to only affect systems running on Windows.
