MaxSez: Pre-Flight Fuel Planning is a necessity if you drive a Trash Hauler even if it’s short haul. This free Basic Planner figures all the factor to include reserve in a simple select aircraft fill in the blank format. It’s the EZ lazy guy quick fix. The link includes a “Load Sheet” Generator & provides a Weight and Balance/Record
which can be saved as a Pilots Log Book addendum… Try it you’ll like it!
Coffin corner (also known as the aerodynamic ceiling  or Q corner ) is the region of flight where a fast but subsonic fixed-wing aircraft’s stall speed is near the critical Mach number, at a given gross weight and G-force loading. In this region of flight, it is very difficult to keep an airplane in stable flight (Buffeting Noted)