What must a commercial pilot hold to legally carry passengers for compensation?

To legally carry passengers for compensation, a pilot must hold a commercial pilot license (CPL). This is because the CPL indicates that the pilot has received the necessary training, has met the required flight experience, and has passed the appropriate examinations to operate an aircraft for hire.

The CPL is specifically designed for pilots who intend to engage in commercial flying activities, which includes carrying passengers for compensation. It empowers pilots with the ability to operate aircraft in more complex situations than those permitted under a private pilot license.

The other options listed do not meet the requirements for carrying passengers for compensation. A private pilot license allows a pilot to fly but does not permit commercial operations. A transport pilot license is generally required for pilots who want to command large, commercial aircraft and typically involves a higher level of training and experience than that of a CPL. A flight instructor certificate, while it allows a pilot to teach others how to fly, does not grant the privilege to carry passengers for compensation on its own.