# Installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder — Aircraft inspection and test intervals under 14 CFR Part 91

For Installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder, interval is Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder; applies to is airplane, or helicopter, in controlled airspace under IFR; consequence if lapsed is No person may operate an airplane, or helicopter, in controlled airspace under IFR; regulation section is § 91.411, verified against its source on 2026-08-06.

- **Inspection or test item:** Installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder _(verified: appears in the quote below)_
- **Interval:** Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder _(verified: appears in the quote below)_
- **Applies to:** airplane, or helicopter, in controlled airspace under IFR _(verified: appears in the quote below)_
- **Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR _(verified: appears in the quote below)_
- **Regulation section:** § 91.411 _(verified: appears in the quote below)_

## What the source says

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter; (2) Except for the use of system drain and alternate static pressure valves, following any opening and closing of the static pressure system, that system has been tested and inspected and found to comply with paragraph (a), appendix E, of part 43 of this chapter; and (3) Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.

## Source

- https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411

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/).