[coldcode]

It's not the cloud per se. It Amadeus, like its rival SABRE, is mostly mainframe based systems (though it has been moving away from that for the past 20+ years). These systems were built in the 1960's. They are actually very reliable but when they go down, they take all their contracted airlines with them. There are only a handful of these companies and those two are the main ones.

[j-tan]

It's a c++ application running against a set of Oracle databases. These are the systems which replaced the older mainframe ones handling check in etc. Some comms with certain mainframe systems managing inventory for some airlines is possible, but less likely for these airlines running altea.

[madeofpalk]

What's the difference between 'cloud' and 'mainframe' systems?

[vec]

About 40 years, give or take.