14 CFR § 91.411
Altimeter system and altitude reporting equipment tests and inspections
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What does 14 CFR § 91.411 require?
14 CFR 91.411 is the 24-calendar-month recurrent test for any airplane or helicopter that is going to be flown IFR in controlled airspace. Three integrated systems are in scope: (1) the static-pressure system that feeds the altimeter + airspeed indicator + vertical speed, (2) the altimeter instrument itself, and (3) the automatic pressure altitude reporting equipment (Mode C / Mode S transponder altitude encoder). All three must be tested + inspected per Appendix E to Part 43 procedures within the preceding 24 calendar months before any IFR flight in controlled airspace. The aircraft can continue VFR with an expired 91.411 — the rule restricts IFR-in-controlled-airspace use, not the airworthiness of the static system itself. Sign-off is restricted: an FAA-certificated repair station with appropriate ratings, a Part 121 or Part 135 holder with continuous airworthiness program, or the manufacturer is required for the altimeter + altitude-reporting tests; an A&P may sign off only the static-pressure-system test, only at the location named in the certificate holder's manual. Logbook entries follow §43.9 + the specific data required by Appendix E. Most operators couple the 91.411 cadence with the §91.413 transponder test (also 24 calendar months) because the avionics shop is doing both simultaneously.
Regulation text (summary)
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 in accordance with Appendix E to Part 43 and found to comply with that appendix. §91.411(a)(2) restricts who may perform these tests to: (1) an FAA-certificated repair station with the appropriate ratings, (2) a Part 121 or Part 135 certificate holder with an approved continuous airworthiness maintenance program, or (3) the manufacturer of the airplane or helicopter. A certificated mechanic with airframe rating (A&P) may perform and certify the static-pressure-system test only — and only at the location described in the certificate holder's maintenance manual.
Read full regulation at eCFR.govWho must comply with 14 CFR § 91.411?
All operators of airplanes + helicopters that fly IFR in controlled airspace — Part 91 private, business, and corporate flight departments; Part 135 commuter + on-demand operators (often satisfied via the operator's continuous airworthiness program rather than directly under 91.411); Part 121 air carriers (satisfied via Subpart L program). VFR-only operators are not required to maintain a current 91.411 test, but if the aircraft has a static system installed and the operator plans any IFR flight, the 91.411 test must be current at the time of that IFR flight. Operators above 18,000 ft MSL (Class A airspace) are inherently IFR and thus inherently subject to 91.411 currency.
What happens if you violate 14 CFR § 91.411?
FAA civil penalties typically $1,500–$25,000 for operating IFR in controlled airspace with an expired 91.411 test; higher for repeat or willful, or where the violation contributed to an incident. By extension, flying IFR with an overdue 91.411 is also a §91.7 airworthiness determination problem — the PIC's pre-flight airworthiness determination is deficient when the required 24-calendar-month altimeter + static + altitude-reporting tests are not current. Airman certificate suspension is possible. Insurance carriers commonly void coverage on IFR flights conducted with an expired 91.411. Aircraft can continue to operate VFR while the 91.411 is overdue, but cannot lawfully accept an IFR clearance.
Penalty range
Annual citations
YoY penalty trend
How to comply (implementation checklist)
- 1Track the §91.411 expiration as the last day of the 24th calendar month after the most recent 91.411 sign-off; quarterly reminders 90 + 60 + 30 + 7 days out so an IFR trip is never planned against an expired test.
- 2Schedule the §91.411 test at an FAA-certificated avionics repair station with the appropriate ratings (or at a Part 121 / Part 135 maintenance facility under that operator's program); confirm the repair station's certificate covers altimeter + static + altitude-reporting ratings before scheduling.
- 3Couple the §91.411 test with the §91.413 ATC transponder test on the same shop visit — both are 24 calendar months and the avionics shop is testing the integrated altimeter + encoder + transponder loop anyway; coupling saves a second downtime + ferry.
- 4Confirm the test procedure complies with Appendix E to Part 43 (static system leak test tolerances, altimeter scale-error check, automatic pressure altitude reporting correlation within 125 feet of pilot's altimeter); request the shop's data sheet showing each tolerance band met.
- 5Verify the §43.9 logbook entry contains: date, total time in service, the words '91.411' or 'altimeter + static system + altitude reporting tests', the next due date (24 calendar months out), the repair station certificate number + ratings, the technician signature, and the maximum altitude to which the altimeter system was tested.
- 6If the operator plans to fly above the maximum altitude to which the altimeter was last tested, schedule a re-test at the higher altitude before that flight — Appendix E ties certification to the maximum tested altitude, not unlimited.
- 7Do not accept an IFR clearance while the §91.411 is overdue; downgrade to VFR until the test is completed and a fresh §43.9 logbook entry is recorded. The cheapest course of action is grounding from IFR, not flying overdue.
Common misinterpretations
- Misinterpretation: '91.411 only applies to IFR-equipped aircraft.' Reality: §91.411(a)(1) is triggered when an airplane or helicopter is operated under IFR in controlled airspace — the test is on the equipment, but the operational trigger is IFR-in-controlled-airspace use, not aircraft equipage. A VFR-only aircraft with a static system installed is not required to maintain 91.411 currency; the same airframe becomes subject to 91.411 the moment an IFR flight in controlled airspace is planned.
- Misinterpretation: '24 months means 730 days from the test date.' Reality: §91.411(a)(1) uses the 24 calendar months convention used throughout Parts 91 + 135. If the 91.411 test was performed on April 8, 2026, it is valid through April 30, 2028 — the last day of the 24th calendar month — not through April 8, 2028.
- Misinterpretation: 'Any certificated A&P can sign off the entire 91.411.' Reality: §91.411(a)(2) restricts the altimeter instrument test + the automatic pressure altitude reporting equipment test to (a) an FAA-certificated repair station with the appropriate ratings, (b) a Part 121 or Part 135 holder with an approved continuous airworthiness program, or (c) the manufacturer. An A&P mechanic may sign off only the static-pressure-system test under §91.411(a)(2), and only at the location described in the certificate holder's manual.
- Misinterpretation: 'Appendix E to Part 43 is a recommended procedure — the avionics shop's process is good enough.' Reality: §91.411(b) makes Appendix E to Part 43 the mandatory test procedure. The shop's process may exceed Appendix E, but cannot substitute for it. Logbook entries must reflect Appendix E compliance — not a vendor-specific procedure that omits required tolerances or test steps.
Real enforcement examples
Anonymized from public FMCSA enforcement summaries. Penalty amounts reflect assessed and final settled values where disclosed.
Part 91 corporate flight department operator was ramp-checked at a Class B reliever airport in 2024 after an IFR arrival; FSDO inspector pulled the maintenance logbook and found the most recent §91.411 entry dated 26 calendar months earlier. Operator received a $11,250 FAA civil penalty for operating IFR in controlled airspace with an expired 91.411 plus a parallel §91.7 airworthiness determination citation. The flight insurance carrier separately declined a claim related to a hangar incident that occurred during the overdue period, citing the 'must be airworthy' clause.
Source: FAA Enforcement Decision Process summaries, anonymized; consistent with FAA Compliance + Enforcement Program reporting in FAA Order 2150.3C
How FileFlo handles 14 CFR § 91.411
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Frequently asked questions
When does the §91.411 test expire?▾
The §91.411 test is valid for 24 calendar months — the last day of the 24th calendar month after the test was performed. If the test was performed on April 8, 2026, it is valid through April 30, 2028. The aircraft becomes ineligible to accept an IFR clearance in controlled airspace on May 1, 2028. The 'calendar months' convention is identical to the §91.409 annual inspection convention — there is no day-of-month grace period.
Who is legally allowed to perform the §91.411 test?▾
§91.411(a)(2) restricts performance to three categories: (1) an FAA-certificated Part 145 repair station with the appropriate ratings (altimeter + static + altitude-reporting), (2) a Part 121 or Part 135 certificate holder with an approved continuous airworthiness maintenance program, or (3) the manufacturer of the airplane or helicopter. A certificated A&P mechanic may perform and sign off the static-pressure-system test ONLY, and only at the location described in the certificate holder's maintenance manual — the A&P cannot certify the altimeter instrument test or the automatic pressure altitude reporting equipment test.
Can I fly VFR with an expired §91.411?▾
Yes — §91.411(a)(1) restricts operating IFR in controlled airspace with an expired test, not VFR operation. The static system, altimeter, and altitude encoder remain installed and functional; the regulation conditions IFR-clearance acceptance on a current 24-calendar-month test. Confirm the §91.413 transponder test is also current if planning VFR flight in transponder-required airspace (Class B, Class C, above 10,000 ft MSL, within 30 NM of Class B primary airport, etc.). The cleanest operational rule for IFR-capable operators: treat 91.411 + 91.413 as a coupled 24-month cadence and never let the aircraft accumulate two overdue tests.
What does Appendix E to Part 43 require?▾
Appendix E specifies the mandatory test procedure for §91.411 compliance. The procedure covers four areas: (1) static system tests — leak rate within tolerance, (2) altimeter scale-error tests across the operational altitude range with documented tolerances at each tested altitude up to the maximum, (3) altimeter case leak + barometric scale error + hysteresis + friction + after-effect tests, and (4) automatic pressure altitude reporting equipment correlation — the encoder output must agree with the pilot's altimeter within 125 feet. §91.411(b) makes Appendix E the mandatory test procedure; shop-specific procedures may exceed Appendix E but cannot substitute for it.
How does §91.411 coordinate with the §91.413 transponder test?▾
§91.411 covers the altimeter + static system + altitude encoder; §91.413 covers the ATC transponder itself. Both are 24 calendar months. The two tests are typically performed on the same shop visit because the avionics technician is exercising the integrated altimeter + encoder + transponder loop in either test. Operators commonly schedule them as one combined event — though they remain legally distinct: each must have its own §43.9 logbook entry, each has its own 24-calendar-month cadence, and an aircraft with a current 91.411 but expired 91.413 is still ineligible to accept an IFR clearance in controlled airspace (because the transponder test gate also applies).
What happens if I accept an IFR clearance with an expired §91.411?▾
Three layers of exposure. (1) FAA enforcement — civil penalty typically $1,500–$25,000 for the operator under §91.411(a)(1); the PIC's airworthiness determination under §91.7(b) is also deficient by extension, opening a parallel §91.7 citation. (2) Airman certificate — suspension is possible, particularly where the operator should have known the test was overdue (clear logbook entry). (3) Insurance — most aviation policies condition coverage on the aircraft being airworthy and required tests being current; carriers commonly void coverage on incidents that occurred while the 91.411 was overdue. The cheapest course is to fly VFR until the next §91.411 test can be scheduled.
Related regulations
Sources + reviewer
Primary source: eCFR.gov — 14 CFR § 91.411
Reviewed by Chad Griffith (Founder + CEO, FileFlo) on