not true.
BA,LH,LX,OS,AF,KL,... all run on AMA
AA runs on Sabre
Its actually the other way around, some airlines have their own system, but most use some sort of GDS.
i.e. even when you make a booking directly with one of the airlines above mentioned, the entire PNR is still created and used in a GDS.
Even when you use Farelogix (for LH NDC bookings for example) the entire PNR also gets created in AMA. When you want to make changes in the LH PNR that FLX does not support yet, you still have to make the changes in the AMA PNR.
Its actually the other way around, some airlines have their own system, but most use some sort of GDS.
i.e. even when you make a booking directly with one of the airlines above mentioned, the entire PNR is still created and used in a GDS.
Even when you use Farelogix (for LH NDC bookings for example) the entire PNR also gets created in AMA. When you want to make changes in the LH PNR that FLX does not support yet, you still have to make the changes in the AMA PNR.