This helpful stack exchange question https://aviation.stackexchange.com/questions/3040/what-are-the-differences-between-various-simulator-levels https://aviatio

This helpful stack exchange question https://aviation.stackexchange.com/questions/3040/what-are-the-differences-between-various-simulator-levels https://aviation.stackexchange.com/questions/3040/what-are-t... and it’s associated answers do a good job outlining the progressively more demanding requirements for an airplane simulator built for use by certified pilots. I have a little background in this myself and the requirements to certify as Level C are tough l, but Level D requirements are quite stringent and rather hard to replicate. ( I did a detailed proposal a decade ago on using cutting edge VR and Haptics to try and cut the operational cost of maintaining multiple simulators for a flight training school. Level D was quite pedantic with respect to the “realism” requirements, we kept running into the requirement to not just look real, sound real, heck even feel real (switch actuation forces), but be real for that exact type of plane. Our argument was that we could reach sufficient fidelity with the haptics and graphics. This was all crazy expensive stuff, but ours would be cheaper crazy expensive stuff ;-) To put it into perspective, in a couple of cases we found it was cheaper to build a Level D simulator by cutting off the entire front of a real second hand plane (finding one with an airframe issue that made it no longer airworthy was the dream) of the desired type, and then wiring up all the switches and displays and electrical stuff to the simulator driving hardware and mounting the entire thing on a huge platform. The cost to buy the plane, cut the front off, tap and splice existing cable harnesses stiffen the cockpit section and overbuild the motion platform was cheaper than reverse engineering the layout with sufficient documentation and wiring a “fake” cockpit with sufficient accuracy including sourcing all the correct parts with the associated paperwork to prove they were all correct. It never went anywhere but it was very educational and has served as a useful perspective as I have observed the rise of the modern VR ecosystem with respect to input and haptics. :-)