Thanks a lot for taking the time for such a detailed response and the references! My first round with flight simulation was in 1998/99 with Sierra Propilot. Back then they would ship it with a 200 page manual that covered all aspects of flight, incl. air navigation. So the website you referred me to feels like home - and the principles haven't changed much either . My current focus is on VFR with Cessna 206, slowly adding night, basic IFR approaches, etc. So probably Plan-G is the best fit for now. EFASS/PFPX look impressive so I would keep them in mind once I'm advanced enough. At least I finally understand how the nav data is organized and why it is different. By the way, did you try simbrief? It's for larger planes but looks great! Thanks again.