I used to work for Sabre, they do a lot more than just bookings, they provide all the software to run an airline basically. I worked in the area for scheduling

I used to work for Sabre, they do a lot more than just bookings, they provide all the software to run an airline basically. I worked in the area for scheduling air crew. But also crossed over into all the flight tracking. Their systems hold a lot of data, though the airlines own and host that data in secure facilities. Fun Facts, when I worked there, you could fly for free on American Airlines ( the company got split out from AA ). They claimed to employ the most PhDs at one time ( lots of operations research). Also claimed to invent database transactions for the problem of people trying to book the same seat on airplanes at the same time (early 60s I believe)