The Altitude Your Transponder Reports Is Not the One on Your Panel

The question is whether a controller can tell when the altimeter setting in your cockpit is wrong, and the answer comes down to the transponder and pressure altitude. That matters as much on a departure out of Palm Beach as on an arrival into Aspen. Controllers have ways to spot an aircraft flying at an altitude other than the one it was assigned, and the check runs through equipment every owner already carries. It doesn't replace setting the altimeter correctly, but it's worth knowing what the facility on the other end of the frequency can see.

With reporting from Flying.