Final answer:
The certification of airman is related to different classes of aircraft.
Step-by-step explanation:
The certification of airman, in relation to aircraft, refers to the process of granting qualifications to individuals to operate and fly different classes of aircraft. In the aviation industry, there are several classes of aircraft including fixed-wing aircraft, rotorcraft (helicopters), gliders, and lighter-than-air (balloons and airships) among others. Each class of aircraft requires specific training and certification for airmen to operate them safely and effectively.