Southwest Airlines said there had been widespread intermittent issues concerning its flights at Ronald Reagan Washington National Airport, but no major disruption.
Computer glitches have hit airlines and airports a number of times over the past few years and analysts say that numerous ticketing systems for airlines as well as other systems they use are very old and can not at times keep up with demand.
"During the morning, we experienced a network issue that caused disruption to some of our systems", the BBC quoted an Amadeus spokesman as saying. Although the network problem has been resolved by Amadeus, airports are cautioning customers that the backup may linger as providers try to get back on track.
A Singapore Airlines spokesman told The Straits Times that it was notified at about 5.30pm about a global outage affecting some of its systems, and that its engineers were working to rectify the issue.
In a Facebook post, Changi Airport said the check-in process may take longer as manual boarding passes have to be issued.
"This was a worldwide failure (of the Amadeus system)". With flights delayed and hundreds of thousands of passengers stranded at airports, the situation has become quite chaotic. A problem with Delta's system grounded flights across the world in January, while a problem with the British Airways system caused thousands of cancellations in May. "That action is ongoing with services gradually being restored", the company noted.