FAR ninety-one dot two thirteen and the broken instrument that might not ground your airplane

What FAR 91.213 Actually Says

FAR 91.213 governs how pilots handle inoperative instruments and equipment. The core principle: not everything on the airplane has to work for the airplane to be legal to fly. A dead second radio, a failed DME unit, or a nonfunctional ADF doesn’t automatically ground the aircraft. But a failed airspeed indicator is a different story entirely.

The regulation provides a structured decision process - a series of filters - to determine whether a specific inoperative item prevents flight.

Filter One: Does the Airplane Have an MEL?

The first question is whether the airplane has a Minimum Equipment List (MEL). An MEL is a document specific to an individual aircraft, approved by the local Flight Standards District Office (FSDO), that spells out exactly which items can be inoperative and under what conditions.

Airlines and larger operators almost always have an MEL. Most training airplanes and privately owned piston singles do not. If your airplane doesn’t have one, you move to the second filter - the four-question test.

The TRAK Test: Four Questions Every Pilot Must Answer

When no MEL exists, FAR 91.213(d) requires you to check whether the inoperative item is required by any of four sources. The mnemonic TRAK makes them easy to remember:

T - Type Certificate Data Sheet (TCDS). Is the item required by the airplane’s type certificate? The TCDS is essentially the aircraft’s birth certificate, listing what the manufacturer says must be installed. The FAA publishes these online.

R - Regulations. Is the item required by any regulation for the kind of flight you’re planning? This is where FAR 91.205 comes in. For day VFR, required instruments include the altimeter, airspeed indicator, magnetic compass, tachometer, oil pressure gauge, oil temperature gauge, fuel gauge for each tank, ELT, and seatbelts. Night VFR adds position lights, anti-collision light, landing light (if for hire), electrical energy source, and spare fuses. IFR adds even more.

A - Airworthiness Directives (ADs). Is there an AD requiring that item to be operational? ADs are mandatory FAA-issued fixes or inspections triggered by identified safety problems.

K - Kinds of Operation Equipment List (KOEL). Found in the Pilot Operating Handbook (POH) or Aircraft Flight Manual, the KOEL lists required equipment by flight category (day VFR, night VFR, IFR). Not every airplane has one, but if yours does, check it.

If the inoperative item is not required by any of these four sources, it can be deferred.

What to Do After You Defer an Item

Deferral isn’t simply ignoring the problem. The regulation requires two specific actions:

1. Deactivate or remove the item. If it’s something simple like pulling a circuit breaker, a pilot can typically handle it. If the deactivation requires any maintenance action, a certificated mechanic must do the work.
2. Placard it as inoperative. A piece of tape with “INOPERATIVE” written on it ensures the next pilot knows that item doesn’t work.

Real-World Scenarios

Dead number-two comm radio, day VFR cross-country. Not required by the type certificate, not listed in FAR 91.205 for day VFR, no applicable AD, and almost no KOEL requires a second comm radio for VFR. Result: deferrable. Pull the breaker, placard it, fly with your number-one radio.

Broken magnetic compass, day VFR. Required by FAR 91.205(a). Result: grounded until repaired.

Burned-out landing light, day VFR, not for hire. Not required by FAR 91.205 for day VFR. Not even required for night VFR unless the flight is for hire. Result: deferrable for a private daytime flight.

Legal vs. Safe: The Question Beyond the Regulation

Even when the airplane is legally flyable with something broken, FAR 91.7 requires the pilot in command to determine that the aircraft is in condition for safe flight. Legal and safe are two different questions.

A landing light might not be required for a daytime flight, but if the flight could run late and end with a landing after sunset, deferring it becomes a safety issue regardless of legality. Good aeronautical decision making (ADM) is the filter that sits on top of every regulatory determination.

Checkride Preparation Tips

The oral exam question on inoperative equipment is nearly guaranteed. Examiners want to see a logical, step-by-step process - not memorized answers. They’re looking for:

• Knowledge of the MEL-first check
• Ability to walk through the TRAK test
• Understanding of the deactivate/remove and placard requirements
• Recognition that the PIC safety determination under 91.7 applies on top of the legal analysis

Practical tip: Keep a copy of FAR 91.205’s equipment lists (day VFR, night VFR, IFR) in your flight bag - a laminated card works well. Practice the scenario with your instructor: pick a broken item, walk through the decision. Do it enough times and it becomes second nature.

Key Takeaways

• FAR 91.213 provides a structured, repeatable process for determining whether inoperative equipment grounds an airplane
• Most GA aircraft lack an MEL, so pilots use the four-question TRAK test: Type certificate, Regulations (91.205), Airworthiness Directives, and KOEL
• Deferred items must be deactivated or removed and placarded - you cannot simply ignore them
• Legal to fly does not mean safe to fly - FAR 91.7 PIC responsibility always applies
• Checkride applicants should practice walking through specific scenarios rather than memorizing vague answers