How long must an ATC transponder be tested and inspected before it can be used?

An ATC transponder must be tested and inspected every 24 calendar months to ensure that it is functioning correctly and meeting the required standards. This time frame is established by the Federal Aviation Administration (FAA) regulations, which mandate periodic checks to confirm that transponders accurately transmit information to air traffic control and other aircraft. Regular testing helps prevent malfunctions that could lead to safety issues during flight operations.

The 24-month interval allows for suitable maintenance and testing, which is crucial since a malfunctioning transponder can compromise situational awareness for both the pilot and air traffic controllers. By adhering to this requirement, pilots ensure they are compliant with regulations and can operate their aircraft safely in controlled airspace.