What makes an aircraft legally airworthy?
Updated · Wingman AeroCare, KFNL
Short answer: Under 14 CFR 3.5(a), an aircraft is airworthy when it conforms to its type design and is in a condition for safe operation. Both conditions must be true. In practice, that means the aircraft matches its approved configuration (including properly documented repairs and alterations), is current on required inspections and applicable ADs, and has nothing wrong with it that makes it unsafe to fly.
The two-part test
1. Conforms to its type design. The aircraft must match the configuration the FAA approved when it was certificated, plus any changes made through approved data, such as supplemental type certificates (STCs), field approvals, or other properly documented major repairs and alterations. An undocumented modification, an unapproved part, or a missing required placard can break conformity even if the airplane flies perfectly.
2. In condition for safe operation. This is about wear, damage, and deterioration: corrosion, cracks, worn control cables, a leaking fuel line, a low-compression cylinder with a burned valve. A perfectly documented aircraft can still be unairworthy if something on it is unsafe.
Who decides?
- The owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition, including compliance with ADs (14 CFR 91.403(a)).
- The pilot in command is responsible for determining whether the aircraft is in condition for safe flight before each flight (14 CFR 91.7(b)), and no one may operate a civil aircraft that is not airworthy (14 CFR 91.7(a)).
- Mechanics and inspectors make the formal airworthiness determination when they approve the aircraft for return to service after maintenance or an inspection.
What has to be current?
For a typical Part 91 piston airplane, legal airworthiness usually depends on:
| Item | Rule |
|---|---|
| Annual inspection within the preceding 12 calendar months | 14 CFR 91.409(a) |
| 100-hour inspection, if used for hire or flight instruction for hire | 14 CFR 91.409(b) |
| All applicable airworthiness directives complied with | 14 CFR 91.403(a), 39.7 |
| Life limits and airworthiness limitations observed | 14 CFR 91.403(c) |
| Transponder test within 24 calendar months | 14 CFR 91.413 |
| Altimeter and static system test within 24 calendar months (for IFR in controlled airspace) | 14 CFR 91.411 |
| ELT inspected within 12 calendar months, battery within date | 14 CFR 91.207 |
What documents need to be on board?
A common memory aid is ARROW, but the actual requirements are narrower than many pilots think:
- Airworthiness certificate, displayed at the cabin or cockpit entrance so it is legible to passengers or crew (14 CFR 91.203(a)(1) and (b))
- Registration certificate (14 CFR 91.203(a)(2)). Since 2023, standard registrations are valid for 7 years.
- Operating limitations, in the form of the approved flight manual, markings, and placards (14 CFR 91.9)
- Weight and balance data, current for the aircraft's equipment
A radio station license is an FCC requirement only for international flights, not an FAA airworthiness item.
What about broken equipment?
An inoperative item does not automatically ground the airplane. For aircraft without a Minimum Equipment List, 14 CFR 91.213(d) lets you fly with inoperative equipment if it is not:
- Required by the aircraft's type certificate or equipment list
- Required by 14 CFR 91.205 for the kind of flight (day VFR, night, IFR)
- Required by the kinds of operations equipment list in the flight manual
- Required by an AD
Even then, the item must be removed or deactivated and placarded "Inoperative," with any removal recorded as required, and a pilot or mechanic must determine it does not create a hazard.
What if the aircraft is unairworthy away from home?
If the aircraft is not airworthy but is capable of safe flight, a special flight permit (ferry permit) under 14 CFR 21.197 can authorize a flight to a place where repairs can be made. Apply through the local Flight Standards office; a mechanic typically must inspect the aircraft and state it is safe for the intended flight.
Why does this matter beyond legality?
Insurance policies commonly require the aircraft to be airworthy for coverage to apply. If an accident investigation finds an expired annual, an overdue AD, or an unapproved modification, coverage can be at risk even if that item had nothing to do with the accident.
How Wingman handles it
At Wingman AeroCare, annuals are performed and signed off by an A&P with Inspection Authorization, and every finding is labeled Airworthy (required to return to service), Recommended, or Optional on your online estimate, with photos and video. That labeling exists for one reason: so you can see exactly where the legal line is and decide everything else on your own terms. Based at Northern Colorado Regional Airport (KFNL). See annual inspections or contact us.