Thanks to David Means for educating me on the use of Fortran (I now also know that its not FORTRAN any more but Fortran too!) in simulators. Quote from David from the Fortran users group on LinkedIn.
"Fortran was for a long time the industry standard language for flight simulation. I used it when I first got into that field in the mid-80's and continued with it until at least 2000. There are a *lot* of flight simulators still running on Fortran all around the world.
The question is one of economics: If you've written code for, say, a 737, you've got a lot of money tied up in the development and testing of the software. So, your first sim is break-even at best. However, once you sign a contract for a second 737 sim, software development cost is minimal as you can just copy everything over from the first one and make minor tweaks as necessary. That's how flight simulation companies make their profits: by selling sims that they've already developed code for. Once you have a lot of sims running a particular code set, there is no incentive to convert it to a different language because a bug fix for one sim can be copied over and fix all the other sims running that same code set.
So, Yes, I have heard of Fortran running real-time simulators. There are thousands of them around the world"