# ATC transponder — Aircraft inspection and test intervals under 14 CFR Part 91

For ATC transponder, interval is within the preceding 24 calendar months; applies to is ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter; consequence if lapsed is No persons may use an ATC transponder; regulation section is § 91.413, verified against its source on 2026-08-06.

- **Inspection or test item:** ATC transponder _(verified: appears in the quote below)_
- **Interval:** within the preceding 24 calendar months _(verified: appears in the quote below)_
- **Applies to:** ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter _(verified: appears in the quote below)_
- **Consequence if lapsed:** No persons may use an ATC transponder _(verified: appears in the quote below)_
- **Regulation section:** § 91.413 _(verified: appears in the quote below)_

## What the source says

> No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with appendix F of part 43 of this chapter; and

## Source

- https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.413

Last verified: 2026-08-06. Review by: 2028-08-05.
Part of [Aircraft inspection and test intervals under 14 CFR Part 91](https://referencesource.org/aircraft-inspection-and-test-intervals/).