Two general aviation pilots get into an airplane… It sounds like the opening to a joke, but it’s not—and you shouldn’t treat it like one. Sharing time in an aircraft with another pilot is much more complicated than jumping in the car for a short hop.
The first time you exercise your pilot in command (PIC) privileges flying with a pilot who is not your flight instructor or a Designated Pilot Examiner (DPE) it can be an eye-opener—especially when the person you are flying with is a certificated pilot of equal or more experience.
