A non-type certificated aircraft's registration marking starts with what letters under PCAR?

In the context of non-type certificated aircraft registration markings under the Philippine Civil Aviation Regulations (PCAR), the correct starting letters for such aircraft is indeed designated as "RP-S."

This designation is specific to non-type certificated aircraft, which are generally aircraft that are not required to meet the same standards as type-certificated aircraft. The "RP" prefix is used for all registered aircraft in the Philippines, and the subsequent letter “S” specifically identifies aircraft that fall under this non-type certification category. This classification is crucial for regulatory bodies to efficiently manage and maintain flight safety standards for different types of aircraft.

Other prefixes, such as "RP-X," "RP-R," and "RP-N," are reserved for other classifications or types of aircraft, which do not apply to non-type certificated aircraft under the current regulations. Therefore, the choice that starts with "RP-S" aligns correctly with the regulatory framework for such aircraft designations.