FAR Ninety-One Point Two Thirteen, the Inoperative Equipment Decision Every Student Gets Wrong, and the Four Questions That Decide Whether Your Airplane Is Legal to Fly

Finding inoperative equipment during preflight does not automatically ground the aircraft. FAR 91.213 establishes a four-question process to determine whether a flight is legal, and a separate obligation under FAR 91.7 requires the pilot in command to judge whether it’s safe. Working both questions is the mark of a prepared pilot in command.

What Does FAR 91.213 Actually Cover?

FAR 91.213 governs inoperative instruments and equipment. It doesn’t say broken means grounded. It provides a legal framework for making that determination systematically, because not every piece of equipment is equally critical to every kind of flight. A broken cabin clock is not the same as a broken altimeter, and the regulation reflects that reality.

The process is four questions, worked in order. A yes on any question means the aircraft is grounded for that item until repaired. Four no answers mean the flight is legally permitted under FAR 91.213 - with two additional requirements that apply before departure.

How Do I Use the Four-Question Process for Inoperative Equipment?

Question 1: Is the equipment required by the aircraft’s Type Certificate Data Sheet or Approved Flight Manual?

Every aircraft is certified with a specific configuration defined in its Type Certificate Data Sheet (TCDS). The Pilot’s Operating Handbook (POH) often includes a Kinds of Operations Equipment List (KOEL), found in the equipment or supplements section, specifying what equipment is required for each type of operation - day VFR, night VFR, or IFR.

If the broken item is listed as required for the type of flight you’re planning, the answer is yes. Get a mechanic before going anywhere. If it’s not listed, or your aircraft doesn’t have a KOEL, move to Question 2.

Question 2: Is the equipment required by FAR 91.205?

FAR 91.205 lists the required instruments and equipment for different types of flight. Day VFR has the shortest list. Night VFR has a longer list. IFR has the most requirements.

The mnemonics taught in ground school - A TOMATO FLAMES for day VFR, for example - are shortcuts to this regulation. If the broken equipment appears on the 91.205 list for the kind of flight you’re planning, the answer is yes and the aircraft is grounded for that item. If not, move to Question 3.

Question 3: Is the equipment required by an Airworthiness Directive?

Airworthiness Directives (ADs) are mandatory maintenance requirements issued by the FAA when a documented safety concern is identified with specific equipment on specific aircraft types. They can require inspection, repair, replacement, or operating limitations. If an AD governs the broken item and hasn’t been complied with, you have a maintenance problem - not just an avionics inconvenience.

For most preflight scenarios in a well-maintained training aircraft, this question will clear cleanly. But ADs represent documented safety findings, and there’s no working around them. If no applicable AD exists for the broken item, move to Question 4.

Question 4: Is the equipment required by any other applicable regulation?

This is the catch-all step that catches pilots who memorize 91.205 and stop there. Several specific requirements live outside of 91.205:

• Emergency Locator Transmitters: required by FAR 91.207
• Transponders with altitude-reporting capability: required in certain airspace by FAR 91.215
• ADS-B Out: required in controlled airspace above 10,000 feet and within the Mode C veil around Class Bravo and Class Charlie airspace

If the broken equipment is required by any specific FAR outside of 91.205, the answer is still yes, and the aircraft is still grounded for that item.

What Are the Requirements Once All Four Questions Clear?

If every answer is no, FAR 91.213 legally permits you to operate with that equipment inoperative. Two steps are required before departure.

First, placard the inoperative equipment. Affix a label reading INOPERATIVE directly on the instrument or switch that isn’t working. This alerts every pilot who sits in that seat after you. It is not optional.

Second, deactivate or remove the equipment if possible. If it’s a circuit breaker item, pull the breaker. If there’s a way to isolate it, isolate it. Inoperative equipment that accidentally cycles on mid-flight creates new problems.

Does Clearing the Four Questions Mean the Aircraft Is Safe to Fly?

Clearing all four questions establishes that the flight is legal under FAR 91.213. That is not the same as airworthy.

FAR 91.7 separately requires the pilot in command not to operate an aircraft in an unairworthy condition. Airworthiness isn’t a checklist - it’s a judgment call that belongs entirely to you. The question to ask honestly: does this broken equipment affect your ability to safely complete this specific flight, on this specific day, in these specific conditions?

A dead turn coordinator on a clear day with flat terrain, a functioning instrument panel, and a solid scan may be a reasonable go decision. The same broken instrument for a lower-time student with a marginal forecast and unfamiliar airspace may produce a different honest answer. The regulation gives you the legal framework. FAR 91.7 gives you the safety question. Both matter, and neither replaces the other.

How Does This Apply to Common Inoperative Equipment Scenarios?

Cabin clock is inoperative. For day VFR, a clock isn’t on the 91.205 required equipment list and isn’t typically required by the TCDS. All four questions clear. Placard it and go. For IFR, the answer changes - IFR equipment requirements include a clock with a sweep second hand or digital equivalent. Different operation, different result.

Landing light is inoperative. Landing lights aren’t required for day VFR under 91.205 in most aircraft. Unless your POH or an AD specifies otherwise, you’ll likely clear all four questions for a daytime flight. For night operations, the FAR 91.7 airworthiness judgment carries significant weight - flying a night approach without a landing light may be technically legal in some cases, but whether it’s smart is a separate question.

Navigation light is inoperative. Navigation lights are required for night operations under 91.205. For a planned day-only flight, you may legally depart - but you’ve just restricted the aircraft. It cannot legally fly at night with a dead nav light. Plan to land before sunset and get it fixed.

Pitot heat is inoperative. For day VFR in visual meteorological conditions, pitot heat isn’t on the 91.205 required list, so technically all four questions can clear. But this is precisely where the FAR 91.7 judgment is decisive. Any possibility of flying into visible moisture, or conditions where ice could form on the pitot tube, means the legal answer and the safe answer are diverging. Don’t rely on the legal answer alone.

Fuel gauges read empty but the tanks aren’t empty. This one does not clear. Fuel gauges are required equipment under FAR 91.205, and they must be accurate. A gauge reading empty when the tanks aren’t is not an inoperative item you placard and work around - it’s an inaccurate required instrument. That aircraft does not fly until it’s corrected.

Do I Need to Log Inoperative Equipment in the Maintenance Records?

If the inoperative equipment doesn’t require maintenance, no logbook entry is needed for the placard itself. Fly the aircraft, and when the item is repaired, that maintenance action gets documented. The placard on a dead clock doesn’t require a mechanic’s signature.

If the inoperative item requires maintenance under an AD, or falls under a required inspection in the aircraft’s maintenance schedule, maintenance must be involved before the aircraft flies. Documentation follows the maintenance work - a placard does not substitute for required maintenance.

How Should I Answer Inoperative Equipment Questions on the Oral Exam?

The Airman Certification Standards (ACS) will put an inoperative equipment scenario in front of you during the oral. The examiner isn’t looking for yes or no - they want the process.

Walk through all four questions. Show where you’d look in the POH for the KOEL. Reference FAR 91.205 by number. Address ADs and the catch-all regulation step. Then, after establishing that the flight is legal, explain FAR 91.7 and the airworthiness judgment. That complete answer separates a confident oral from a stumbling one.

The preflight isn’t only about physical condition - it’s also about legal status. A beautifully maintained aircraft can be technically illegal for the flight you’re planning because of a single inoperative item. Knowing FAR 91.213 means you work the process instead of getting surprised on the ramp.

Primary references: FAR 91.213, FAR 91.205, and your aircraft’s POH - specifically the equipment list and any KOEL.

Key Takeaways

• FAR 91.213 provides a four-question framework for inoperative equipment decisions; broken does not automatically mean grounded.
• Work the questions in order: TCDS/AFM requirement → FAR 91.205 → Airworthiness Directives → any other applicable regulation.
• If all four questions clear, placard the item as INOPERATIVE and deactivate it if possible - both steps are required by the regulation.
• FAR 91.7 requires a separate airworthiness judgment from the PIC; legal to fly and safe to fly are not always the same answer.
• Fuel gauges that read incorrectly are not an inoperative item - they are an inaccurate required instrument, and the aircraft does not fly until corrected.