If it's like the airline reservation terminals I'm familiar with, it will be using a 6-bit bisync serial multidrop protocol under the Airline Link Control (ALC) protocol umbrella. Searching for ALC, PARS, IPARS, TPF & SITA P1024B should give you all sorts of interesting info.
In theory, you could still hook it up to something. It's like an IBM 3270 terminal in that it's a block-mode terminal that requires a controller (called a PAD). You could find an ALC PAD; they're still made or you could find a used one from someone like CR Systems. As late as Cisco IOS 12.4, ALC PAD code was in the Cisco IBM feature set if you had the right physical interfaces in your router; I don't know about IOS 15 or later. Probably other routers could do that too. That gets the terminal talking on a network. But then, as far as I know, you really need a mainframe running TPF or the equivalent to get the terminal to do anything useful. Maybe TPF could run on the Hercules emulator; I've never heard of anyone trying that.
Talk to Linux? I dunno...maybe terminal->PAD->token ring/X.25/sync serial->Linux->tn3270. Just a guess, but I doubt it.
If all that doesn't put one off, the keyboard is undoubtedly completely proprietary. If you don't have it, it's unlikely to be documented anywhere well enough to adapt something else. That's probably a show stopper.