Final answer:
FAR 91.413 requires the certification of an aircraft's transponder every 24 months, essential for air traffic safety and management.
Step-by-step explanation:
The requirement for the certification of an aircraft's transponder can be found in the Federal Aviation Regulations (FAR). Specifically, FAR 91.413 deals with ATC transponder and altitude reporting equipment tests and inspections. Airplanes are required to have their transponders tested and inspected every 24 calendar months to ensure they are functioning correctly and in compliance with the specified performance standards. This is necessary for the safety and management of air traffic as transponders play a crucial role in the identification and altitude reporting of the aircraft within controlled airspace.
The requirement to have an aircraft's transponder certified is contained in FAR 91.413. According to this regulation, all aircraft operating in controlled airspace must have an operable transponder and must be inspected and certified within a specified timeframe.