There is a difference between Hosting Systems and GDS's. GDS's distribute airlines that are not necessarily hosted by the GDS, and charge the airline a segment fee. Part of the segment fee is paid as an incentive to the travel agent, its all very complicated. The main GDS's are Amadeus, Sabre, Galileo and Worldspan. The segment fee varies by market but is not usually more than a few Euros. Most GDS's are based on airline inventory systems, but with greatly expanded functionality for cars, hotels etc etc.
Hosting systems host the inventory of an airline - this is where sales made in GDS's are communicated to, and where information is stored and passed to the Departure Control and other Res Control systems. The main Hosting systems are Sabre (AA, AS
and loads of others), Worldspan (DL, NW
), SHARES (CO, VS
), SITA Gabriel (hundreds of smaller carriers), OpenSkies (LCC's - very limited connectivity to GDS's though), plus a lot of in-house legacy systems. The big hosting systems (Sabre, Worldspan) are the clunky dinosaurs from the 70's. The newer ones are pretty limited, things like GDS connectivity are not as good as the big systems. Everyone and his dog seems to be developing hosting systems, but between you and me they're not very good.
Amadeus has a slightly different hosting setup - 1A 'hosts' about 140 airlines (known as Altea Sell carriers), but for distribution purposes only. GDS and external systems booking these airlines communicate the bookings to Amadeus, and Amadeus travel agents book space as well, and 1A forwards all the bookings to the real inventory systems of those 140 airlines - spread between AF
(Lufthansa Systems), AY
(RESIBER), and SITA Gabriel. Altea Sell carriers are charged either a segment fee or a revenue-passenger-boarded fee.
and their 20 hosted airlines are at the moment moving their Inventory functions from QUBE to the Amadeus Altea Plan platform, which is a new Inventory hosting platform within Amadeus - BA
and several others will be moving over shortly as well.
Young and beautiful and thin and gorgeous AND BANNED ! Cya at airspaceonline.com, losers