FAR ninety-one dot two oh five and the required instruments checklist that every examiner asks about

FAR 91.205 defines the minimum instruments and equipment required before an aircraft can legally fly. For VFR day flight, the memory aid A TOMATOFLAMES covers all 13 required items: airspeed indicator, tachometer, oil pressure gauge, magnetic compass, altimeter, temperature gauge (liquid-cooled engines), oil temperature gauge, fuel gauge, landing gear position indicator (retractable gear), anti-collision lights, manifold pressure gauge (altitude engines), ELT, and safety belts. For VFR night, add the FLAPS items: fuses, landing light (for-hire only), anti-collision lights, position lights, and source of electrical energy.

Why Does FAR 91.205 Matter Beyond the Checkride?

This regulation determines whether your airplane is legal to leave the ground on any given day. Getting it wrong doesn’t just fail an oral exam — it grounds the airplane until whatever is missing gets fixed. The regulation is organized in layers: all flight, then VFR day, then VFR night, then IFR. Each layer builds on the previous one, adding required items.

What Does Each Letter in A TOMATOFLAMES Stand For?

A — Airspeed indicator. Required to know your speed. No airspeed indicator, no flight.

T — Tachometer. One for each engine. Displays engine RPM for proper power management.

O — Oil pressure gauge. One for each engine. Oil pressure is the primary indicator of engine health. Without it, there’s no way to detect a developing engine problem.

M — Magnetic compass. Not the heading indicator, not the GPS. The magnetic compass requires no electricity and no vacuum pressure — it works independently using the earth’s magnetic field.

A — Altimeter. Must be a working, adjustable altimeter set to the current altimeter setting before every flight.

T — Temperature gauge. For each liquid-cooled engine. Most training aircraft (Cessna 172, Piper Cherokee) use air-cooled engines, so this requirement often doesn’t apply. Know whether your specific airplane has a liquid-cooled or air-cooled engine — the examiner may ask.

O — Oil temperature gauge. One for each engine. Different from oil pressure. Oil pressure confirms the oil is circulating; oil temperature confirms it’s within operating range. Both are required.

F — Fuel gauge. One for each tank, indicating fuel quantity. Fuel gauges in small aircraft are notoriously unreliable. The gauge satisfies the legal requirement, but always visually check your tanks during preflight and dip them if possible.

L — Landing gear position indicator. Only required for aircraft with retractable landing gear. Fixed-gear trainers don’t need one. In retractable-gear aircraft like a Piper Arrow or Cessna 182 RG, you’ll typically see three green lights — one for each gear — that must all illuminate before landing.

A — Anti-collision lights. An approved aviation red or white anti-collision light system is required for aircraft certificated after March 11, 1996. For older aircraft, check the type certificate. A burned-out anti-collision light is a regulatory issue, not just an inconvenience.

M — Manifold pressure gauge. Required for each altitude engine — essentially any engine with a constant-speed propeller. Basic trainers with fixed-pitch props won’t have one and don’t need one.

E — ELT (Emergency Locator Transmitter). Required for most flights, with exceptions listed in FAR 91.207. The ELT battery must be replaced when the transmitter has been used for more than one cumulative hour or when 50% of the battery’s useful life has expired. The expiration date should be marked on the outside of the unit.

S — Safety belts. Plus shoulder harnesses for each front seat if the aircraft was manufactured after July 18, 1978. A seatbelt that doesn’t latch properly grounds that seat — and potentially the airplane if you don’t have enough functioning seats for your passengers.

What Additional Equipment Is Required for VFR Night Flight?

For night operations, everything from the VFR day list applies plus the items in the FLAPS mnemonic:

F — Fuses. One complete set of spare fuses, or three of each kind required, accessible to the pilot in flight. If the aircraft uses circuit breakers instead of fuses, this requirement doesn’t apply. Know the difference: a fuse blows and must be physically replaced; a circuit breaker pops and can be reset.

L — Landing light. Required only when the aircraft is operated for hire. For private pilots flying at night, a landing light is not legally required — but flying at night without one is a poor decision regardless of what the regulation says.

A — Anti-collision lights. Already on the day list, but emphasized for night operations where visibility to other aircraft is critical.

P — Position lights. Red on the left wing, green on the right wing, white on the tail. These navigation lights tell other pilots your direction of travel and are non-negotiable for night flight. They follow the same convention used in maritime navigation.

S — Source of electrical energy. A functioning alternator or generator and an adequate battery. At night, losing electrical power means losing lights — other aircraft can’t see you and you can’t see the runway. This is why alternator failures at night are treated as serious emergencies.

What Happens When a Required Instrument Is Inoperative?

When a required instrument fails, FAR 91.205 intersects with FAR 91.213 (inoperative instruments). If the failed item is on the required equipment list, the airplane cannot fly until it is fixed, deactivated and placarded, or covered by a special flight permit.

Consider these scenarios:

• Oil temperature gauge stuck during preflight: The gauge is on the required list. The airplane is grounded. The stuck gauge might be a simple malfunction — or it might be frozen in place while the engine overheats. That uncertainty is exactly why the regulation exists.
• Left position light out before a night cross-country: Position lights are required for night flight. All three must function. Replace the bulb, test it, then fly. No judgment call here.
• ELT battery expired by three months at annual inspection: Even if the ELT works perfectly, an expired battery means the ELT doesn’t meet the regulatory requirement. Replace the battery before the next flight.

The regulation requires items to be both installed (physically present) and operable (functioning). A fogged, unreadable airspeed indicator is installed but not operable. A compass removed for repair is not installed. Both situations ground the airplane.

What About the Type Certificate and Equipment List?

FAR 91.205 sets the baseline, but your specific airplane may have additional requirements based on its type certificate. The Pilot’s Operating Handbook contains an equipment list in Section 6, where some items are marked as required. Those requirements stack on top of the 91.205 list. A thorough preflight means checking everything your specific airplane needs to be airworthy — not just the mnemonic.

What About GPS, Transponder, and Radio?

For VFR day flight, none of these appear on the 91.205 list. Transponders are required in certain airspace under FAR 91.215. Radios are required for controlled airspace operations. These are separate regulations with separate requirements that layer on top of the 91.205 equipment baseline.

How Should I Study This for the Checkride?

The Airman Certification Standards test this under preflight preparation. The examiner wants to see that you can determine airworthiness, identify inoperative equipment, and understand the process for dealing with it.

The most effective study method: sit in your training airplane with the POH open. Go through A TOMATOFLAMES letter by letter and physically point to each instrument or piece of equipment. Touch the airspeed indicator. Find the tachometer. Locate the ELT. Check the seatbelt mechanisms. Then do the same for FLAPS — find the fuse box or confirm circuit breakers, locate the landing light switch, check position lights during the walk-around, trace the electrical system to the alternator and battery. When each letter connects to something real in the cockpit, the list stops being abstract.

Key Takeaways

• A TOMATOFLAMES covers all 13 required items for VFR day flight under FAR 91.205
• FLAPS adds the five additional items required for VFR night operations
• If any required item is inoperative, the airplane is grounded until it’s fixed, placarded, or permitted — no exceptions
• Your airplane’s POH equipment list may add requirements beyond the 91.205 baseline
• Transponders, radios, and GPS are governed by separate regulations, not 91.205