Passengers checking in online at Vietjet's kiosks at Nội Bài International Airport in Hà Nội. — VNA/VNS Photo

Several airline websites worldwide were inaccessible early in the afternoon of July 19.

As of 3:30 PM, Vietjet Air reported that from approximately 11:30 AM to 2:30 PM (Vietnam time) on July 19, a global Microsoft cloud system failure affected booking and online check-in for airlines worldwide.

By 2:30 PM, the system was back online, but some airlines were forced to adjust their schedules and others experienced delays because of the earlier problems in the chain.

Vietjet Air stated that the Microsoft system error was beyond the control of the airline and its customers. Passengers with travel plans on July 19, are advised to monitor the 'My Flight' section on www.vietjetair.com and the Vietjet Air mobile app and contact the hotline for assistance if needed.

Microsoft later announced that it had identified the cause and restored most of the system, but warned: "Some customers may still experience issues, including with Microsoft 365 and Teams".

According to Reuters, after Microsoft's confirmation, several major US airlines issued notices of flight suspensions citing "communication problems".

The airlines have not provided details on the number of affected flights. Data from the flight tracking site FlightAware shows that Frontier canceled 147 flights and delayed 212 others. Allegiant had 45 per cent of its flights delayed, while Sun Country experienced delays across 23 per cent of its schedule. — VNS