Team LES, the Saab 340A is without a doubt my favorite aircraft in XP10. Thank you! I was looking at it in plane maker, not to make changes, just to see what the SFC was, and noticed that the critical altitude was 8500'. If Specific Fuel Consumption (SFC) is the same at "low altitude" or "high altitude" for turboprops and critical altitude is 8500' (max altitude at which the engine can put out its maximum allowable power), but the service ceiling is 25,000', why would one ever want to fly above 8,500'? I interpret this to mean that as long as terrain and ATC aren't issues, I would want to fly no higher than 8,500'. I suspect that I really need to learn to read the charts, something I've never had to do. Thanks for your enlightening explanations.