Pitot-Static & Transponder Checks
FAR 91.411 and 91.413 inspections explained: what IFR owners need every 24 months, who can sign them off, and where the traps are.
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Updated July 16, 2026
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The two familiar 24-calendar-month checks are separate rules with different operating triggers:
- 14 CFR 91.411 covers the static pressure system, altimeters and automatic pressure-altitude reporting system for an airplane or helicopter operated in controlled airspace under IFR.
- 14 CFR 91.413 covers an ATC transponder used under the operating rules referenced in that section.
They are often completed together and casually called a “pitot-static/transponder check.” That shop shorthand should not hide which system was tested, which rule applies to the planned operation or what the maintenance record actually certifies.
91.411 and 91.413 side by side
| Question | 91.411 | 91.413 |
|---|---|---|
| System covered | Static pressure system, each altimeter and automatic pressure-altitude reporting system | ATC transponder |
| Main operating trigger | Airplane or helicopter in controlled airspace under IFR | Use of a transponder specified in 91.215(a), 121.345(c) or 135.143(c) |
| Recurring interval | Within the preceding 24 calendar months | Within the preceding 24 calendar months |
| Test standard | Part 43 appendices E and F | Part 43 appendix F |
| Additional test trigger | Certain opening/closing of the static system; work where altitude-data correspondence error could be introduced | Installation or maintenance where data-correspondence error could be introduced |
The rules overlap around altitude reporting, but one inspection is not a word-for-word substitute for the other.
What “24 calendar months” means
The interval is measured in calendar months, not 730 days. A test completed at any time in July starts its calendar-month window from July for tracking purposes. The signed entry, test date and applicable rule remain the records to use; do not infer currency from an unlabeled panel sticker.
If a shop performs both inspections, the records should make both scopes clear. An invoice that says only “IFR cert” may be convenient shorthand, but it is weaker evidence than entries that identify the systems, test standards and return-to-service basis.
91.411 is not a generic inspection of every pitot component
Owners often call 91.411 the pitot-static check. The regulation itself names the static pressure system, altimeter instruments and automatic pressure-altitude reporting system. Its recurring operating restriction applies to airplanes and helicopters in controlled airspace under IFR.
The word choice matters because a broader inspection of pitot lines, drains, heat, airspeed indicators or angle-of-attack equipment may arise from the aircraft's maintenance programme, manufacturer instructions, an airworthiness directive or troubleshooting—not from the recurring text of 91.411 alone.
Section 91.411 also adds event-driven checks. Subject to its stated exceptions, opening and closing the static pressure system requires a leakage test to the relevant part of Appendix E. Installation or maintenance on the automatic pressure-altitude reporting system, where data-correspondence error could be introduced, requires an integrated-system test.
91.413 follows transponder use
Section 91.413 says a covered ATC transponder may not be used unless it was tested and inspected within the preceding 24 calendar months and found to comply with Part 43 Appendix F.
That is why “I only fly VFR” is not, by itself, a complete transponder-currency analysis. The question is whether the planned operation uses a transponder under the operating provisions referenced by 91.413, including the equipment and airspace requirements in 91.215.
The transponder rule also has an event trigger: after installation or maintenance where a data-correspondence error could be introduced, the integrated system must be tested to the applicable Appendix E standard. A recent 24-month check does not erase that post-maintenance requirement.
Who can perform the work
The authorisations differ by scope. Section 91.411 lists the aircraft manufacturer, appropriately rated and equipped repair stations, and a certificated mechanic with an airframe rating for static pressure system tests and inspections only. Section 91.413 lists appropriately equipped repair stations with the specified ratings, certain continuous-airworthiness programme holders and, in a limited installation case, the aircraft manufacturer.
That means “my mechanic can sign it” is too broad. The provider needs the privilege, rating and equipment for the exact test being performed.
Owner checklist before an IFR trip
- Read the last entries for both 91.411 and 91.413 rather than relying on a due-date sticker.
- Confirm the test month and the systems identified in each entry.
- Check whether static-system, altitude-reporting or transponder work occurred after those tests.
- Match the inspection status to the intended airspace and operating rule.
- If the records or post-maintenance test status are unclear, resolve them with an appropriately authorised provider before the flight.
ADS-B Out performance and configuration are related operational issues, but a satisfactory ADS-B report does not replace the inspections required by 91.411 or 91.413. Keep the ADS-B operating requirements and the inspection records as separate controls.
Bottom line
The clean distinction is not “IFR check versus another IFR check.” Section 91.411 controls the static, altimeter and altitude-reporting systems for specified IFR operations; 91.413 controls the covered transponder use. Both commonly carry a 24-calendar-month interval, and both can require another test after relevant maintenance.
Track the two entries separately and review them after avionics or static-system work. The planned operation—not the label on the invoice—decides which rule matters.
