Something interesting I came upon used by the 747(and allegedly some A300B4-200s as well) is the LTN-92, a sort of hybrid between a conventional INS(like the Carousel IV-A) and an FMC. From what I can tell reading up on it, it basically just functions like an INS, but uses 5 letter codes for coordinates instead of manually implementing them via lat/long yourself, and can carry up to 99 waypoints in a flightplan as opposed to only 9 at a time for the IV-A. It was also one of the original laser ring gyro INS systems, so it had significantly lower drift rate. Apparently there is enough documentation out there for another developer of a 747 to have plans to implement it, so I was curious if JF could think of modelling it as a bit of an expansion, and as a possible drop in to the A300 as well as any other possible future developments that may have used it(like the DC-10). I think if given some more awareness, there may be enough interest in it being added, as it's mildly easier to operate than an INS, and could easily have modern waypoints in it, as opposed to the nonstandard waypoints that may have been used IRL.