As a real world pilot, I do my own flight planning the old fashioned way. I generally try to put in realistic winds, then interpolate and use an E6B to do my flight planning. I have found XP10 to give me ground speeds comperable to what I had figured on, but I notice that flying times tend to go too long. My flight time increases about 10 minutes every hour over what my flight planning says it should be. Very confusing, as speed and distance tell me one thing but XP10 does something else. I am flying only general aviation single-engine props, as that's what I really fly. Has anyone else noticed this? Thanks!