I can't be much help, but I doubt the 9-pin connector is RS232 serial. The patent describes using an Arcnet LAN for communication with the central computer. No mention is made of RS232 as an external interface. Arcnet is a token-passing bus network and not something you can just plug into a PC and bring up a terminal.
The video/audio interface is likely similar to a cable TV signal. Multiplexed channels on differing frequencies. Not something easy to use without really knowing the fine details.
The patent isn't really much help because it's a block diagram with only suggestions of what components and protocols to use, and it's clearly a complex system. Fascinating, though. My tiny experience on aircraft systems predates this by a fair bit. What you need is actual schematics and pinouts.
You might get lucky and someone around here will have worked on the system... would be an interesting project.