I think BA was the first company to use Altéa, but it is now very widely used. FLY was a joint BA - Amadeus project for a bespoke version of Altéa which handles a lot of BA quirks that the first level of Altéa didn't have, and which was also customised to BA's processes and procedures. Amadeus did the coding, but under a joint spec with BA, as I understand it.