How often must a transponder be inspected?

How often must a transponder be inspected?

• A. Every 12 months
• B. Every 24 months
• C. Every 48 months
• D. At installation only

Answer: (B)

Regular checks of the transponder are required to keep radar and altitude data accurate for air traffic control. The standard interval for a transponder test and inspection is every 24 calendar months. This means it should be tested roughly every two years to verify it still responds correctly with the right codes and altitude data, and that the encoder and related circuitry are within limits. The inspection isn’t just about initial installation; ongoing verification catches drift or wear that could affect surveillance. That’s why a 24-month interval is used instead of yearly or longer spans, and it isn’t limited to installation only.

Regular checks of the transponder are required to keep radar and altitude data accurate for air traffic control. The standard interval for a transponder test and inspection is every 24 calendar months. This means it should be tested roughly every two years to verify it still responds correctly with the right codes and altitude data, and that the encoder and related circuitry are within limits. The inspection isn’t just about initial installation; ongoing verification catches drift or wear that could affect surveillance. That’s why a 24-month interval is used instead of yearly or longer spans, and it isn’t limited to installation only.