Definition
A required inspection and test of the aircraft's transponder system, performed every 24 calendar months by an authorized technician under 14 CFR 91.413, to confirm the unit transmits correct identification and altitude data to air traffic control radar.
Plain English
A check, done at least every two years, that proves the aircraft's transponder is still working accurately enough to be used in controlled airspace.
Context Anchor
You encounter this during preflight planning when checking required aircraft inspections and maintenance records before flight.
Derivation
Transponder is a blend of 'transmitter' and 'responder' — a device that responds by transmitting when interrogated by ground radar. 'Certification' here means a formal sign-off that the equipment meets required standards.
Why Pilots Care
A current certification is required for flight in most controlled airspace and ensures the transponder will reply correctly to ATC radar and TCAS queries.
Intuition Check
Certification here does not mean the pilot is being certified. It means the aircraft’s transponder has been tested, passed, and recorded as current.
Example Sentence 1
Before the cross-country, the pilot checked the logbook and confirmed the transponder certification was current within the last 24 calendar months.
Example Sentence 2
After the annual inspection the mechanic updated the transponder certification so the aircraft could operate in Class B airspace.