The Stopped Clock on Preflight, FAR Ninety-One Point Two Thirteen, and the Four-Question Decision Flow That Tells You Whether to Fly or Call Your A and P

Federal Aviation Regulation 91.213 governs inoperative equipment and provides a clear, step-by-step decision framework for determining whether an aircraft can legally fly with something broken. Most pilots know the regulation exists but struggle to apply it correctly when standing on the ramp with a broken instrument and a flight planned. Knowing the process before that moment arrives is essential.

What Is FAR 91.213 and When Does It Apply?

FAR 91.213 applies any time an instrument or piece of equipment is inoperative - discovered during preflight or after takeoff. It applies to general aviation aircraft operating under Part 91, and it gives the pilot in command a structured method for making the go/no-go call.

The regulation does not simply say “placard it and fly.” It requires a specific analysis that checks multiple sources before any inoperative item can be legally deferred.

Does Your Aircraft Have an Approved MEL?

The first question is whether the aircraft has an approved Minimum Equipment List (MEL).

A MEL is a formal, FAA-approved document specifying which instruments and equipment can be inoperative while the aircraft remains legal to fly, and under what conditions. Airlines, corporate flight departments, and Part 135 charter operators routinely operate under MELs. The MEL is aircraft-specific, and the safety analysis behind it has already been reviewed and approved by the FAA.

If an MEL exists for the aircraft, consult it first. The MEL tells you whether the flight can proceed and what steps may be required.

The reality for most general aviation pilots: the rental Cessna 172, the club Cherokee, the personally owned Piper or Mooney almost certainly does not have an approved MEL. If none exists, move to the alternative procedure in the regulation.

What Equipment Is Actually Required? The Four Sources to Check

This is where the regulation does its real work. FAR 91.213 allows an inoperative item to remain on the aircraft only if it is not required. That single word - required - drives the entire analysis. One source is not enough. There are four.

1. FAR 91.205

FAR 91.205 lists the instruments and equipment required for each category of operation:

• 91.205(b): Day VFR
• 91.205(c): Night VFR
• 91.205(d): IFR

For day VFR, many pilots learned the memory aid ATOMATOFLAMES: Airspeed indicator, Tachometer, Oil pressure gauge, Manifold pressure gauge (if the engine requires it), Altimeter, Temperature gauge for liquid-cooled engines, Oil temperature gauge for air-cooled engines, Fuel gauge for each tank in use, Landing gear position indicator (retractable gear only), Anti-collision lights, Magnetic direction indicator, ELT, and Safety belts. The exact list is in the regulation - read it directly when making this call.

For night VFR, add position lights, a landing light (if flying for hire), a source of electrical energy, and spare fuses.

For IFR, the list expands to include a generator or alternator, gyroscopic rate of turn indicator, gyroscopic pitch and bank indicator, gyroscopic direction indicator, two-way radio, and navigation equipment appropriate to the route.

A stopped clock does not appear on the day VFR list under 91.205(b). But 91.205 is only the first of four sources.

2. The Type Certificate Data Sheet and Aircraft Flight Manual

Some equipment is part of an aircraft’s original type certificate. If the type certificate data sheet (TCDS) or aircraft flight manual (AFM) lists a specific piece of equipment as required, it is required - full stop.

For basic trainers, the TCDS is unlikely to enumerate every cockpit instrument. For complex aircraft with integrated avionics suites or factory-installed autopilots, the documentation can be very specific. Know what your aircraft’s documentation actually says.

3. Airworthiness Directives

Airworthiness directives (ADs) are legal requirements. If an active AD requires a specific instrument or piece of equipment to be functional for flight, the aircraft cannot fly with it inoperative.

Check the aircraft maintenance records for any ADs applicable to the item in question. For a stopped clock, this is unlikely. For an ELT, an autopilot component, or certain avionics, verify before assuming.

4. The POH Limitations Section and KOEL

The pilot’s operating handbook - specifically the limitations section - and, if the aircraft has one, the Kinds of Operations Equipment List (KOEL) must be consulted.

The KOEL is a table in the POH that breaks out required equipment by day VFR, night VFR, and IFR. If the KOEL marks an item as required for the intended operation, the flight does not happen with that item broken.

One critical detail: the KOEL is aircraft-specific. Two Cessna 172s parked side by side can have different avionics installations, which means different KOELs. Generic model knowledge is not sufficient - you need the documents for the specific aircraft you are flying.

How Do You Make the Hazard Determination?

After clearing all four required-equipment sources, the regulation imposes one more obligation: the pilot in command must determine that the inoperative item does not constitute a hazard to the flight.

Not required and not a hazard are two separate determinations.

A stopped clock on a day VFR flight? A phone or EFB tracks the time. No real hazard.

A failed ammeter is a different question. The ammeter itself may not appear on the day VFR required list, but the electrical system it was monitoring absolutely matters to the flight. The broken indicator may not be the issue - the underlying system condition might be. FAR 91.213 permits flying with a broken gauge. It does not permit flying with a broken system. If the condition of the underlying system cannot be determined, that may be a no-go even when the indicator itself is not technically required.

Think this through honestly every time.

How Do You Placard and Document an Inoperative Item?

Once the analysis confirms the item is not required and not a hazard, the regulation requires the item to be placarded as inoperative before departure.

A formal printed placard is not required. A strip of masking tape marked INOPERATIVE placed near the instrument satisfies the regulation. It notifies the next pilot of a known squawk and demonstrates that a deliberate, informed decision was made.

An entry must also be made in the aircraft maintenance records noting the item as inoperative and citing FAR 91.213 as the authority. This entry belongs in the aircraft records - not the pilot’s personal logbook - because the aircraft’s operational status lives in the aircraft records.

Who Can Make This Determination - and When Is a Mechanic Required?

Under FAR 91.213, the pilot in command can make the inoperative equipment determination without a certificated mechanic present. A stopped clock does not require an A&P to confirm it does not affect airworthiness.

The line that matters: if removing or deactivating the equipment constitutes maintenance under Part 43, that work must be performed by an appropriately certificated person - an A&P, or a pilot who holds an appropriate certificate. Pulling wiring or disconnecting components is maintenance. Pulling a circuit breaker to deactivate something, adding a placard, and flying is generally acceptable in many situations - but the exact line matters and is item-specific.

In most straightforward cases, the cleanest approach is to leave the item physically in place, add the inoperative placard, and make the maintenance record entry. Clean, legal, and traceable.

Real-World Scenarios

Compass with a bubble. The fluid has leaked and the compass reads erratically. The magnetic direction indicator is on the day VFR required list under 91.205(b). This is a no-go. No amount of 91.213 analysis changes that. The flight does not happen until a mechanic addresses it.

OAT gauge inoperative. On a day VFR flight in a basic piston trainer, the outside air temperature gauge is typically not on the required equipment list for day VFR - unless the specific KOEL says otherwise. If it is not required, placard it, make the entry, and the flight can proceed.

ELT squawk. The ELT has its own regulation, FAR 91.207, with its own provisions for malfunctioning ELTs - specific conditions and time limits. An ELT issue is not a pure 91.213 analysis. Read FAR 91.207 directly for that item.

Red X on a glass panel, IFR flight. Whether that display is required depends on the specific aircraft, avionics installation, KOEL, and approaches available on the route. If the failed display is the sole source of attitude information and the route requires it, the flight does not go. If the aircraft has redundancy and the KOEL shows the item as not required for IFR, work through the full process. This is precisely the scenario where knowing the specific aircraft documentation is not optional.

What If Equipment Fails In-Flight?

FAR 91.213 applies to in-flight failures as well as preflight discoveries. If an instrument fails after takeoff, the same framework applies: determine if it is required for the continued operation and intended flight, determine if it constitutes a hazard, and make the pilot-in-command decision.

A mid-flight instrument flag does not automatically require declaring an emergency and diverting - as long as the analysis confirms the flight can continue safely and legally. If the failure affects a required system for the operation, the plan must be adapted accordingly.

How Do Examiners Test FAR 91.213 on a Checkride?

Examiners test this during the oral, and the standard for a passing answer is demonstrating the regulation as a process, not a memorized phrase.

A question like “on your preflight you notice the turn coordinator has a flag - what do you do?” is not answered with “I placard it and fly.”

The correct answer walks through each step: Check FAR 91.205 for the operation being conducted. Consult the POH and KOEL. Look for any applicable airworthiness directives. Determine whether deactivation or removal requires maintenance under Part 43. Make the hazard determination. Placard the item. Document it in the aircraft records.

The Airman Certification Standards (ACS) for private pilot covers required instruments and equipment. Expect to be tested on it, and be prepared to walk through the steps out loud.

What Is the Difference Between Required Equipment and Airworthiness?

These two concepts are related but distinct, and conflating them is a common error.

Airworthiness refers to the overall condition of the aircraft - structural integrity, flight control rigging, engine condition. An airworthiness certificate does not expire; it was issued when the aircraft was manufactured. An annual inspection certifies the aircraft was airworthy at the time of that inspection. Anything that changes or fails between annuals is the pilot’s responsibility to evaluate on every preflight.

Required equipment refers to the specific instruments and systems that must be functional for a particular type of operation.

An aircraft can be airworthy with a non-functional clock. It cannot be airworthy with structural damage or compromised flight controls, regardless of what any equipment list says.

The 91.213 analysis asks whether a specific item is required. Running simultaneously - separately, on every preflight - is the broader question: is this aircraft airworthy? Both questions must be answered every single time.

Key Takeaways

• FAR 91.213 is a step-by-step process, not a judgment call made from memory. Know it before you need it.
• Check four sources to determine if an item is required: FAR 91.205, the type certificate data sheet and AFM, any active airworthiness directives, and the POH/KOEL for the specific aircraft.
• Not required and not a hazard are two separate determinations - both must be made before any item can be deferred.
• Placard inoperative items before the flight and record them in the aircraft maintenance records citing FAR 91.213; the entry belongs in the aircraft records, not a personal logbook.
• The pilot in command can make the inoperative equipment determination; any maintenance required to physically remove or deactivate the item must be performed by an appropriately certificated person under Part 43.