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Before using a required ATC transponder, how recently must it have been tested and inspected?

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  1. Within the preceding 24 calendar months
  2. Every 12 calendar months
  3. Every 100 hours

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References

  1. 14 CFR 91.413 ATC transponder tests and inspections www.ecfr.gov/current/title-14/section-91.413 Checked 2026-10-09.

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