When it comes to preflighting an airplane, there is nothing more true. Sure, you can follow the diagram laid out in the pilot’s operating handbook, or routinely drone through a do-list of items a mile long that are spelled out in the aircraft’s preflight check list, but if you don’t understand what problems you are looking for, what’s the point?

The preflight check is not a skill you need to master just to pass a check ride or flight review; it’s a skill you need to have to become and remain a safe pilot. It involves inspecting for mechanical faults, sure, but there are certain things you also must do or know before each flight. Simple stuff, like how will the aircraft perform in these conditions, or have I done this before?
