This part applies to all charter flights, and all other flights carrying charter passengers or cargo, in interstate and/or foreign air transportation by U.S. certificated air carriers or in foreign air transportation by foreign air carriers. It does not apply to any flights performed by a commuter air carrier, air taxi operator, or certificated air carrier operating “small aircraft” under part 298 of this chapter. Nothing in this part gives authority to operate a type or level of service not authorized by certificate, foreign air carrier permit, or exemption, except that a certificated air carrier authorized to conduct scheduled operations may conduct charter flights, in interstate and/or foreign air transportation, without limitation as to the points served.