Altimeter and static system test, 24 calendar months.

What the rule says

14 CFR 91.411(a)(1): no person may operate an airplane or helicopter in controlled airspace under IFR unless "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." The count is by calendar month: a test in March 2025 is good through March 31, 2027.

A correction to the keyword

The rule is not a general airworthiness test for every flight. It applies to IFR operations in controlled airspace. Two other triggers sit in the same paragraph: after any opening and closing of the static pressure system (except system drain and alternate static pressure valves), the system must be tested and inspected; and after installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder where data correspondence error could be introduced, the integrated system must be tested.

Who can do the test

Under 91.411(b), the manufacturer of the aircraft; a certificated repair station properly equipped and holding the instrument rating Class I, a limited instrument rating appropriate to the make and model, a limited rating appropriate to the test, or an airframe rating appropriate to the aircraft; or a certificated mechanic with an airframe rating, for static pressure system tests and inspections only.

Other points

• Equipment approved under Technical Standard Orders is considered tested and inspected as of its date of manufacture (91.411(c)).
• No one may operate in controlled airspace under IFR above the maximum altitude at which all altimeters and the automatic altitude reporting system have been tested (91.411(d)).

Worked example

Test and inspection on March 18, 2025. The 24th calendar month after March 2025 is March 2027, so the last day is March 31, 2027. An IFR flight in controlled airspace on April 2, 2027 needs a new test first.

Transponders have their own 24-month test: see the transponder test due date page.

FAQ

How often is the altimeter and static system test required?

Within the preceding 24 calendar months, for IFR operations in controlled airspace under 14 CFR 91.411(a).

Is the test required for VFR flight?

Not under 91.411. The rule applies to operation under IFR in controlled airspace.

Does the test expire on the anniversary day?

No. It is good through the end of the 24th calendar month after the month of the test.

Who is allowed to do the test?

The aircraft manufacturer, a properly rated repair station, or for static pressure system tests a certificated mechanic with an airframe rating.

What else triggers a static system test?

Any opening and closing of the static pressure system, except drain and alternate static valves, and some transponder altitude reporting maintenance.

Sources

Retrieved 2026-11-02. Regulation text read through the eCFR API (current as of 2026-10-29); AIM text read from the FAA publication URL below. Rules change; check the current text.

• 14 CFR 91.411, Altimeter system and altitude reporting equipment tests and inspections: the 24 calendar month rule, who may test, TSO equipment and altitude limits.