Who must hold a Medical Certificate?

Any person exercising the privileges of any of the following certificates: airline transport pilot certificate, commercial pilot certificate, private pilot certificate, recreational pilot certificate, flight instructor certificate (when acting as pilot in command if serving as a required pilot flight crewmember), flight engineer certificate, flight navigator certificate, or student pilot certificate.

Except for a person employed by the FAA, a branch of the military services or the Coast Guard, a person acting as an air traffic control tower operator also must hold a medical certificate.