FAR Ninety-One Point Two Oh Five, the Required Equipment List That Has Different Answers for Day and Night, and the Nuances Behind the Mnemonic Every Student Recites Without Really Understanding

FAR 91.205 defines the minimum instruments and equipment that must be installed and functioning before a flight is legal. The regulation carries separate requirements for day VFR and night VFR - and the distinctions matter on a preflight, on a checkride, and in the air when something stops working.

What Is FAR 91.205 Actually Doing?

FAR 91.205 is a floor, not a checklist. It does not describe everything useful in the cockpit or everything you’d want on a long cross-country. It defines the absolute minimum. If any item on the applicable list is broken or missing, the flight is not legal until that item is addressed.

The mechanism for handling broken equipment is a separate regulation, FAR 91.213, which governs inoperative instruments and equipment. But 91.205 is where the standard is set.

The regulation is divided by flight condition. Subsection (b) covers VFR day operations. Subsection (c) covers VFR night operations. The night list builds on the day list and adds specific requirements that frequently catch pilots off guard.

What Equipment Is Required for Day VFR?

The mnemonic most ground school students learn is ATOMATOFLAMES. Each letter maps to a required item, but several carry conditions and exceptions that the mnemonic obscures.

A - Airspeed indicator. Required. Measures speed through the air, not over the ground.

T - Tachometer, for each engine. One per engine. On a normally aspirated aircraft, this is how power is set.

O - Oil pressure gauge, for each engine that uses a pressure lubrication system. Almost every reciprocating engine in general aviation qualifies. If this gauge fails in flight, you have a required instrument that is no longer functional.

M - Manifold pressure gauge, for each altitude engine. This one carries a critical condition: “altitude engine” means a supercharged or turbocharged engine. A normally aspirated engine - the kind powering a standard Cessna 172 or Piper Cherokee - does not require a manifold pressure gauge under 91.205. Some trainers have one installed anyway, but if it fails on a normally aspirated aircraft, you are not in violation of the required equipment list.

A - Altimeter. Required. An altimeter that fails in flight is not a gray area - it is a required instrument that is no longer functioning.

T - Temperature gauge, for each liquid-cooled engine. The vast majority of GA training aircraft use air-cooled engines (Lycoming, Continental). This item applies to liquid-cooled engines, which includes some Rotax-powered aircraft. If you’re flying a standard trainer, this requirement likely does not apply to your airplane.

O - Oil temperature gauge, for each air-cooled engine. This is the counterpart. Air-cooled Lycomings and Continentals require an oil temperature gauge. This one does apply to most GA trainers.

F - Fuel gauge indicating quantity in each tank. Not a low-fuel light. Not a general indication that fuel is present. The regulation requires a gauge showing quantity in each tank. If one gauge on a two-tank aircraft fails, you have an issue.

L - Landing gear position indicator, if the aircraft has retractable landing gear. Fixed-gear aircraft are exempt - there is nothing to indicate. If the aircraft has retractable gear, the position indicator is required.

A - Anti-collision light system. For small civil airplanes certificated after March 11, 1996, an approved aviation red or aviation white anti-collision light system is required for day VFR. Aircraft certificated before that date are not subject to this requirement under subsection (b). The date that matters is certification date, not manufacture date.

M - Magnetic direction indicator. The magnetic compass. Required. It is the backup to the heading indicator and the original navigation instrument.

E - Emergency Locator Transmitter (ELT). Technically, the ELT requirement lives in FAR 91.207, not 91.205. It belongs in any equipment discussion because it is required for most general aviation flights - but its precise regulatory home is section 207, not 205.

S - Safety belts. Approved safety belts are required for each occupant two years of age or older. A separate requirement applies to shoulder harnesses: small civil aircraft manufactured after July 18, 1978 must have approved shoulder harnesses for each front seat. An older aircraft built before that date may not legally require them. Know your airplane’s manufacturing date.

What Additional Equipment Is Required for Night VFR?

Night VFR under subsection (c) adds the following items on top of the full day list:

Position lights. The red light on the left wing, green on the right wing, and white on the tail. These are required after dark, without exception. They allow other aircraft to determine your orientation.

Anti-collision light system. At night, the strobe or rotating beacon is required regardless of the aircraft’s certification date. The March 11, 1996 cutoff applies only to the day VFR requirement in subsection (b). After dark, all aircraft must have it.

Landing light, if the aircraft is operated for hire. A private pilot flying for personal reasons at night is not required to have a functioning landing light under this regulation. If compensation is involved for carrying passengers, it goes on the required list.

Adequate source of electrical energy for all installed electrical and radio equipment. If the electrical system has a known deficiency, it becomes a material preflight consideration before any night departure.

Spare fuses. Either a spare set, or three spare fuses of each kind required, accessible to the pilot in flight. If the aircraft uses circuit breakers instead of fuses, this item does not apply. Most modern GA aircraft use circuit breakers, but older aircraft with fused electrical systems must carry spares.

How Do You Apply This on a Preflight?

When a preflight reveals a questionable instrument or component, run through three questions before making a go-no-go decision.

First: Is this item on the required equipment list for this flight condition - day VFR, night VFR, or IFR?

Second: Does the aircraft’s Pilot’s Operating Handbook or approved flight manual list this item as required for airworthiness?

Third: Is there a minimum equipment list or kind-of-operations (KOEL) list applicable to this aircraft that addresses the item?

If any of the three says the item is required and it is broken, the aircraft is grounded until it is fixed. If all three say the item is not required, there is a legal pathway - though not necessarily the right decision.

As an example: if a preflight reveals a stuck outside air temperature (OAT) gauge, that instrument does not appear on the 91.205 VFR day required list. The flight is not illegal on that basis alone. But if the altimeter shows an unexplained error of 300 feet from field elevation, the analysis is different. The altimeter is required. An altimeter that does not function accurately is a go-no-go item.

What Happens If Required Equipment Fails in Flight?

FAR 91.7 requires the aircraft to be airworthy throughout the entire operation. The required equipment standard does not only apply at the moment of takeoff. If a required instrument fails en route, the aircraft is no longer operating with its required equipment functional.

If an altimeter fails in flight in uncontrolled airspace, the pilot cannot legally continue into Class B, C, or D airspace without the required equipment functioning. The appropriate response is to advise ATC, declare the situation if warranted, and land as soon as practicable.

As pilot in command under FAR 91.3, you hold the final authority over the operation. The required equipment list defines the legal minimum. Nothing prevents a pilot from deciding that a known-bad instrument - even one not on the required list - is sufficient reason to cancel a flight. The regulations set the floor. Judgment sets everything above it.

How Does This Appear on a Checkride?

The Airman Certification Standards for the private pilot certificate, specifically the preflight inspection area of operation, requires applicants to identify discrepancies that affect airworthiness. A DPE may point to a flagged squawk in the maintenance logbook and ask the applicant to reason through whether the flight is legal. They may present a hypothetical about a failed gauge.

Knowing which items have conditional applicability - manifold pressure for altitude engines only, temperature gauge for liquid-cooled engines only, anti-collision light by certification date, shoulder harnesses by manufacture date - is what separates a confident answer from a hesitant one.

Key Takeaways

• FAR 91.205 sets the minimum required instruments for VFR flight; FAR 91.213 governs how to handle inoperative equipment
• The manifold pressure gauge is only required for supercharged/turbocharged engines; most GA trainers are normally aspirated and exempt
• The night VFR list adds position lights, anti-collision lights (regardless of certification date), landing light if for hire, adequate electrical source, and spare fuses if applicable
• The March 11, 1996 certification date determines day VFR anti-collision light applicability; the July 18, 1978 manufacture date determines shoulder harness requirements
• If a required instrument fails in flight, FAR 91.7 means the airworthiness obligation continues - landing is the correct course of action, not continuing and sorting it out later