Tailwind. — An aviation study journal

What must be installed and operative for a given kind of flight. Four interlocking rules do the work: 91.205 sets the day and night VFR baselines, 91.207 covers the ELT, 91.209 governs when lights must be on, and 91.215 / 91.225 layer on transponder and ADS-B Out for the airspace flown.

Day VFR equipment

For day VFR in a standard-category airplane, the required instruments and equipment are enumerated — thirteen items walked by the A-TOMATO-FLAMES mnemonic in the toggle below.

Two certification-date traps

Anti-collision lights are required for day VFR only on small civil airplanes certificated after March 11, 1996
Shoulder harnesses for front seats are required only on small civil airplanes manufactured after July 18, 1978

Toggle Day ↔ Night below to see what each subsection of 91.205 requires; hover or focus an item for the requirement text, rationale, and CFR cite.

Airworthiness · PA.I.B.K3

ATOMATOFLAMES — Day & night VFR equipment

The minimum equipment required under §91.205. Grouped by when you fly — day at all times, night adds FLAPS.

Altimeter

Altimeter — sensitive type, adjustable for current pressure.

§91.205(b)(5)

Day VFR— required for all VFR ops

§91.205(b)

+ Flaps— add these at night

§91.205(c)

ATOMATOFLAMES defines required day-VFR equipment under §91.205(b); FLAPS adds five items at night under §91.205(c). Hover any tile to see its requirement and CFR subsection.

Night additions

Night VFR requires the day list plus the items in . The mnemonic is FLAPS — five items:

Two flags: the landing light is required only when operated for hire, and the anti-collision lights requirement at night applies to all aircraft regardless of certification date — pre-1996 aircraft still need them after dark.

Emergency locator transmitters

An ELT is required on most U.S.-registered civil airplanes .

Inspection and battery

Inspect every 12 calendar months — installation, battery, controls, crash sensor, antenna signal
Battery replaced (or recharged) after 1 cumulative hour of use or at 50% useful life
Up to 90 days without an ELT while removed for inspection — logbook entry and placard required

Narrow exceptions

Training within 50 NM of departure
Design and testing
New aircraft delivery
Single-occupant aircraft

Position and anticollision lights

EQUIPMENT · 14 CFR 91.205 / 91.209 · PA.I.B.K3

Aircraft exterior lights

Position lights, their regulatory coverage arcs, and the anticollision beacon.

PLATE 22 · EXTERIOR LIGHTS

Position lights

Red left · green right · white aft. Required on from sunset to sunrise (91.209).

Anticollision beacon

Red or white flashing. On for all operations, day and night — unless the PIC judges it safer off (91.209(b)).

Strobes

Co-located with the wingtip position lights on most trainers. Courtesy: off in the pattern and on the ground near others at night.

Coverage arcs per 14 CFR 23.1385–1397 series: 110° each wingtip, 140° tail — together a full 360° so every observer sees at least one light and can read your direction of flight.

The lights rules sit in :

Position lights — on from sunset to sunrise (not the 1-hour-after / 1-hour-before window used for night currency under 61.57(b))
Anti-collision lights — on whenever operating; PIC may turn off if doing so is in the interest of safety (e.g., reflecting in cloud)
Moored or anchored at night in an unlit area — anchor light visible 3 SM

Transponder

A Mode C (or Mode S) altitude-encoding transponder is required in:

Class A, B, and C airspace
The Mode C veil — within 30 NM of a Class B primary airport, surface to 10,000 ft MSL
At and above 10,000 ft MSL in the 48 contiguous states (excluding airspace at and below 2,500 ft AGL)

ADS-B Out

ADS-B = Automatic Dependent Surveillance–Broadcast. ADS-B Out broadcasts your aircraft's GPS position, altitude, and velocity once per second to ATC and to other ADS-B-equipped aircraft. It replaces and augments traditional radar surveillance.

Required in essentially the same airspace as the transponder :

Class A, B, and C
Mode C veil
At and above 10,000 ft MSL in the contiguous 48 (excluding ≤2,500 AGL)
Class E over the Gulf of Mexico from the coast out to 12 NM, at and above 3,000 ft MSL

Two equipment flavors

1090ES (1090 MHz Extended Squitter) — required for Class A; works at all altitudes; same frequency as Mode S transponders, often integrated
UAT (Universal Access Transceiver, 978 MHz) — only permitted below 18,000 ft MSL; common in light GA

ADS-B In is optional — it receives free FAA broadcasts: traffic (TIS-B) and weather and NOTAMs and TFRs (FIS-B) when within range of a ground station. ADS-B In doesn't satisfy 91.225; only ADS-B Out does.

All of these rules apply simultaneously. governs what to do when something on these lists is inoperative — covered in PA.I.B.R1.

Worked examples:

Day VFR in a 1985 Cessna 172 — Aircraft is certificated pre-1996, so no anti-collision lights required for day; manufactured post-1978, so shoulder harness required for front seats. The classic A-TOMATO-FLAMES list applies minus the anti-collision. Standard six-pack plus tach, fuel gauges, oil pressure, mag compass, ELT, and safety belts covers the day requirement.
Night VFR in a 1972 Cessna 172 — Adds FLAPS to the day list. Anti-collision lights ARE required at night despite the pre-1996 certification date — no exception for night. Position lights on from sunset to sunrise. Spare fuses on board. Landing light NOT required (personal use, not for hire). Pre-1978 manufacture means no shoulder harness mandate, though most modern Cessnas in service have been retrofitted.

Day & night VFR equipment