FAR Ninety-One Point Two Oh Five, the Required Equipment List Every Checkride Candidate Gets Tested On, and the Inoperative Instrument Rule That Decides Whether You Fly or You Don't

FAR 91.205 governs the instruments and equipment required aboard civil aircraft for legal flight operations. It organizes requirements by type of operation - day VFR, night VFR, and IFR - and knowing it thoroughly is essential for both the private pilot oral exam and every real-world preflight decision that follows.

What Does FAR 91.205 Require for Day VFR?

The standard memory aid for day VFR required equipment is the acronym ATOMATOFLAMES. Each letter stands for a required item, but understanding why each is there is more durable than memorizing letters alone.

A - Airspeed Indicator. Every performance callout in the aircraft flight manual - rotate speed, best rate of climb, best angle, approach speed, flap extension speeds - is an airspeed. The airspeed indicator keeps the pilot above stall speed and below never-exceed speed at all times.

T - Tachometer (one per engine). In a fixed-pitch aircraft like a Cessna 172, the tachometer is the primary power reference for climb, cruise, and approach settings. An irregular RPM response to throttle input is also a data point - pay attention to it.

O - Oil Pressure Gauge (one per engine using a pressure system). Oil pressure dropping out of the green arc is not a situation to monitor and investigate later. It is an emergency developing in real time.

M - Manifold Pressure Gauge (altitude engines only). A turbocharged or supercharged engine requires active management of intake pressure, making this gauge required. In a normally aspirated trainer, full throttle equals full atmospheric pressure at the intake - no manifold pressure gauge is needed.

A - Altimeter. Set to the current altimeter setting before every flight and verified against the published field elevation. The FAA permits a tolerance of plus or minus 75 feet against field elevation with the correct setting dialed in. Outside that range, the altimeter needs attention before the aircraft departs.

T - Temperature Gauge (liquid-cooled engines only). Most piston training aircraft are air-cooled, making this item easy to skip during oral prep. If the aircraft has a liquid-cooled powerplant, this gauge is required.

O - Oil Temperature Gauge (air-cooled engines). This applies to every Lycoming and Continental in a training aircraft. Oil lubricates the engine and plays a significant role in cooling it. Climbing oil temperature above the green arc requires attention - whether that means increasing airspeed, checking oil quantity, or investigating something more serious.

F - Fuel Gauge (quantity, each tank in use). The regulation requires a working, accurate gauge - a broken gauge that reads full when the tank is empty does not satisfy this requirement. Even a functional gauge is not a substitute for knowing how much fuel was loaded, tracking flight time, and doing the math. Use the gauge as one reference, not the only one.

L - Landing Gear Position Indicator (retractable gear aircraft only). Fixed-gear pilots don’t need this. The moment a pilot steps up to a retractable, it’s required. Gear-up landings are among the most common and most preventable accidents in general aviation.

A - Anticollision Light System. This requirement applies only to aircraft whose type certificate was issued or applied for after March 11, 1996. Aircraft certified before that date are not required to have one installed for day VFR. However, if an aircraft has a functioning anticollision light, it must be turned on during operations. Know which side of that certification date your aircraft falls on.

M - Magnetic Direction Indicator. The compass operates completely independent of the electrical system. When avionics fail and the battery goes dark, the compass is still working. That independence is exactly why it’s required.

E - Emergency Locator Transmitter (ELT). Technically the ELT requirement lives in FAR 91.207, not 91.205 - but the two regulations are grouped closely enough on oral exams that both must be known. Know the battery inspection interval, the expiration requirement, and where the manual activation switch is located.

S - Safety Belts. Every occupant must have one available. The pilot and front-seat occupants must have them fastened during takeoff and landing. The distinction matters: available for all occupants, fastened for front-seat occupants during critical phases of flight.

What Additional Equipment Is Required for Night VFR?

FAR 91.205(c) adds four requirements for night VFR operations on top of the day VFR list.

Approved position lights (navigation lights): Red on the left wingtip, green on the right wingtip, white showing aft. These steady-burning lights communicate direction of travel - red means another aircraft is looking at your left side, green means they are looking at your right. Required from sunset to sunrise.

Approved anticollision light system: Unlike the day VFR rule, the night VFR anticollision light requirement applies to every aircraft, regardless of certification date. At night, conspicuity is everything - the flashing beacon or strobe is one of the primary ways other traffic sees you in a dark sky.

Adequate source of electrical energy for all installed electrical and radio equipment. Before a night cross-country, account for the full load: nav lights, anticollision light, avionics, interior lighting, transponder. An alternator failure at night presents a fundamentally different problem than the same failure in daytime.

Approved electric landing light - but only if the aircraft is operated for hire. A private pilot flying a personal aircraft on a night flight has no legal requirement for a working landing light. The FARs are a floor, not a ceiling. Flying onto a dark runway without a landing light is a bad idea regardless of what the regulation says or does not say. Know where the legal minimum is, then build personal minimums well beyond it.

How Do You Handle Inoperative Equipment?

FAR 91.213 governs inoperative equipment and provides a four-step decision process every pilot should be able to walk through without hesitation.

Step 1 - Check for an FAA-approved Minimum Equipment List (MEL). Most general aviation training aircraft don’t have one; charter and commercial operators often do. If a MEL exists and permits flight with the item inoperative under specific conditions, follow those conditions precisely. If the MEL lists the item as required, the aircraft is grounded until repaired.

Step 2 - Check the Kinds of Operations Equipment List (KOEL) in the aircraft’s Pilot’s Operating Handbook (POH). The KOEL specifies what equipment is required for each type of operation. If the broken item is listed as required for the planned flight, it must be repaired before departure.

Step 3 - Check FAR 91.205 for the kind of operation planned. If the item is on the required list for day VFR, night VFR, or IFR - whichever applies - the aircraft does not fly until it’s repaired.

Step 4 - Check for an applicable Airworthiness Directive (AD). ADs are legally binding maintenance requirements issued by the FAA. If an AD requires a piece of equipment to be operational, there is no flexibility. Comply or ground the aircraft.

If the inoperative item clears all four tests - not required by the MEL, not required by the KOEL, not on the 91.205 required list for the planned operation, and not the subject of a binding AD - the pilot may deactivate it, placard it as inoperative, and continue. The placard is not optional, and it is not a logbook note or a mental reminder. It must be a physical placard in the aircraft so any subsequent pilot who flies it is aware of the condition.

What Does the Inoperative Equipment Rule Look Like in Practice?

Working through specific scenarios makes the four-step process concrete.

Clock stops working. Not on the day VFR required list. Check the KOEL - not there. No applicable AD. Placard it and fly. Use a watch or phone for any required timing.

Turn coordinator fails. Not on the day VFR required list. Check the KOEL for the specific aircraft. If clear, placarding it and continuing day VFR may be legal. But if there is any possibility of instrument meteorological conditions (IMC) anywhere along the route, a failed turn coordinator changes the risk calculation significantly. Know the regulation, then apply judgment on top of it.

Altimeter malfunctions. On the required list. The aircraft is grounded until the altimeter is repaired and tested.

Left nav light burns out during a night preflight. Position lights are on the night VFR required list. The aircraft does not fly at night until the light is repaired. For any daytime operation under consideration, run the four-step test.

What Does the Examiner Want to See on the Oral?

The Airman Certification Standards (ACS) for the private pilot certificate address required equipment directly in the preflight procedures task. The examiner is not checking whether the applicant can recite a mnemonic. They are checking whether the applicant can reason through a regulation and arrive at a legal, informed decision.

Walk the examiner through FAR 91.213. Show the four-step process. Demonstrate that you know which items are required for the planned operation and that you have a structured method for evaluating anything that is not working. That is the answer they are looking for.

Key Takeaways

• ATOMATOFLAMES covers day VFR required equipment under FAR 91.205(b); night VFR adds position lights, an anticollision light system, adequate electrical energy, and - for aircraft operated for hire only - an approved electric landing light.
• The FAA altimeter tolerance is ±75 feet against published field elevation with the correct altimeter setting dialed in.
• The anticollision light certification-date cutoff (March 11, 1996) applies only to day VFR. For night VFR, every aircraft must have an approved anticollision light system regardless of certification date.
• A private pilot on a personal night flight has no legal requirement for a working landing light - but the FARs establish a minimum, not a standard of safety.
• When equipment is inoperative, work through the four-step process in order: MEL → KOEL → FAR 91.205 → Airworthiness Directives. If the item clears all four, placard it physically in the aircraft before flying.