Federal Aviation Regulation Ninety-One Point Two Oh Five, ATOMATOFLAMES, and Why the Mnemonic You Memorized for the Written Test Is Actually the Morning Checklist for Airworthiness

FAR 91.205 is the legal definition of whether your aircraft is airworthy on any given morning. It establishes the minimum required instruments and equipment for general aviation aircraft operating under visual flight rules. If any item on the list is inoperative, the aircraft cannot legally fly - full stop.

What Does FAR 91.205 Require for Day VFR Flight?

The regulation is organized in two tiers: what your aircraft needs for day VFR, and what it additionally needs for night VFR. Most flight instructors teach the day list using the mnemonic A TOMATO FLAMES - fourteen letters representing fourteen required items.

A - Airspeed Indicator. Required. You need to know how fast you are going.

T - Tachometer. One for each engine. For most training aircraft, that means one tachometer for one engine. The “for each engine” language matters in multi-engine aircraft.

O - Oil Pressure Gauge. One for each engine that uses a pressure system. A zero reading at run-up is one of the few indications that should unconditionally stop a departure.

M - Magnetic Compass. The only navigation instrument on the required list that needs zero electrical power to function. Every other panel instrument - the attitude indicator, heading indicator, GPS, comm radios - can fail when the alternator quits and the battery drains. The wet compass keeps working. Understanding its behavior, including northerly turning errors and acceleration/deceleration errors, is not just a checkride item. It is a genuine survival skill.

A - Altimeter. Required. You need to know how high you are.

T - Temperature Gauge. Required for each liquid-cooled engine only. Most training aircraft use air-cooled Lycomings or Continentals, so this item typically does not apply.

O - Oil Temperature Gauge. Required for air-cooled engines. This is a separate item from the liquid-cooled temperature gauge - the two cover different cooling architectures. You need the right one based on what is under your cowling. You do not need both.

F - Fuel Gauges. Required to indicate quantity in each tank in use. Not a single fuel gauge - one for every tank the aircraft is actively drawing from. That phrasing has real consequences, covered below.

L - Landing Gear Position Indicator. Required only for aircraft with retractable landing gear. Fixed-gear aircraft skip this item entirely. For retractables, the pilot must be able to positively confirm gear position before touchdown.

A - Anti-Collision Light. For aircraft manufactured after March 1, 1996, an anti-collision light system - rotating beacon or strobe - is required for all flights, including day VFR. Aircraft manufactured before that date were grandfathered, but check the logbooks. If anti-collision lighting was added after manufacture and listed as required equipment, it is required.

M - Manifold Pressure Gauge. Required only for altitude engines - supercharged or turbocharged powerplants. Naturally aspirated engines do not require this gauge under 91.205.

E - ELT (Emergency Locator Transmitter). FAR 91.205 lists the ELT as required, but the governing details live in FAR 91.207. That regulation has provisions pilots frequently overlook: the ELT battery must be replaced or recharged after more than one hour of cumulative use, and must be replaced when 50% of its manufacturer-rated battery life has been consumed. There is also a 12-month inspection requirement. Flying with an expired battery or a unit that has not been inspected in over 12 calendar months means the aircraft is not airworthy.

S - Safety Belts. Required for all occupants. For aircraft manufactured after July 18, 1978, shoulder harnesses are required for the pilot and front-seat occupants in addition to lap belts. Both must be serviceable. The data on what a properly worn shoulder harness does in a deceleration event is compelling - it keeps people alive in accidents that would otherwise be fatal.

What Additional Equipment Is Required for Night VFR?

Night VFR adds to the day list. The acronym for the additional items is FLAPS.

F - Fuses. One spare set or three spare fuses of each kind required for the aircraft. They must be accessible to the pilot in flight - not in the baggage compartment, not in a flight bag on the ramp.

L - Landing Light. Required only if the aircraft is operated for hire. Private pilots flying their own aircraft at night are not legally required to have a working landing light under this rule. That said, deer on runways and taxiway confusion at dark unfamiliar airports are real hazards. Turn the landing light on.

A - Anti-Collision Light. Already covered in the day VFR list.

P - Position Lights. Navigation lights: red on the left wing, green on the right wing, white on the tail. These are absolutely required for night flight and are a separate item from the anti-collision system. Both must be operating for a legal night flight.

S - Source of Power. An adequate electrical power source for all required electrical and radio equipment. If the alternator is out and the aircraft is running on battery alone, assess carefully whether sufficient electrical capacity exists for the planned flight - particularly if there is any chance of picking up an instrument clearance.

What Happens When Required Equipment Is Inoperative?

This is where the regulation matters most in practice. Consider two scenarios.

Scenario one: A Cessna 172 has a fuel gauge for the left tank stuck at zero. The tank is confirmed full by visual inspection at the fuel cap. Can the flight depart?

No. FAR 91.205 requires fuel gauges showing quantity for each tank in use. A broken fuel gauge means the aircraft is not airworthy, regardless of what the pilot can see at the fuel cap.

Scenario two: The cabin overhead light is burned out. Can the flight depart for a day VFR trip?

Yes, in most cases. A cabin light is not on the FAR 91.205 required equipment list. Under FAR 91.213, inoperative equipment that is not required by the applicable operating rules and not required by an airworthiness directive or type certificate data sheet can be deferred - provided it is removed or deactivated and placarded inoperative in plain sight of the pilot, with a maintenance logbook entry made.

The fuel gauge cannot be deferred. The cabin light can. A checkride examiner will hand a pilot exactly this type of scenario and watch how they reason through it - not whether they can recite the list from memory, but whether they can identify which list the item is on, whether an AD applies, and what the deferral process looks like.

Does FAR 91.205 Cover Everything My Aircraft Needs to Be Airworthy?

FAR 91.205 is a minimum standard - it sets the regulatory floor. Your specific aircraft may have additional requirements above that floor.

The type certificate data sheet, the approved flight manual or pilot’s operating handbook, and any applicable airworthiness directives can all impose requirements the pilot in command is obligated to meet. After confirming that the aircraft meets FAR 91.205, the next step is confirming it also meets everything specific to that make and model.

The annual inspection is signed off by a certificated mechanic, required every 12 calendar months under a separate regulation. But on any given morning, the determination that the aircraft is airworthy and legal to fly rests with the pilot in command. That authority is inseparable from the responsibility.

Why Does This Regulation Matter Beyond the Checkride?

Every item on the A TOMATO FLAMES list is there because of what happens when aircraft fly without it.

The magnetic compass requirement exists because pilots lost orientation when electrical instruments failed and had nothing to fall back on. The ELT requirement exists because search and rescue teams spent days locating aircraft that a working transmitter could have found in hours. The shoulder harness requirement exists because engineers and accident investigators studied survivable crashes and found people who should have walked away - and did not - because deceleration forces drove them into the panel.

These regulations are not administrative formalities. They are the institutional memory of hard lessons, written down so the next generation of pilots does not have to learn them the same way.

Key Takeaways

• A TOMATO FLAMES covers the 14 required instruments and equipment items for day VFR under FAR 91.205; FLAPS covers the additional items required for night VFR.
• A broken fuel gauge is not deferrable - it makes the aircraft not airworthy. A non-required item like a cabin light can be deferred under FAR 91.213 with a logbook entry and inoperative placard.
• The ELT battery must be replaced when 50% of its manufacturer-rated life has been consumed, and the unit requires a 12-month inspection under FAR 91.207 - check the maintenance logbook.
• Anti-collision lights are required for all flights - including day VFR - on aircraft manufactured after March 1, 1996.
• FAR 91.205 is a regulatory floor, not a complete airworthiness checklist. The POH, type certificate data sheet, and applicable airworthiness directives may impose additional requirements. The airworthiness call belongs to the pilot in command.