Night Windows & UTC
Sunrise, sunset and civil twilight for an airport or position, and the FAA, EASA and UK night windows side by side in Zulu and local time.
Loading the tool…
Choose an airport (type a code, a name or a city) or switch to latitude and longitude, set the date and, if the device guess is wrong, your own time zone. The tool shows sunrise, sunset, solar noon and the beginning and end of civil twilight for that date, then the night that begins that evening and ends the next morning under five different rules. Every time is shown three ways: Zulu (UTC), local time at the airport and local time where you are.
The rules do not agree, and that is the point. The currency window of 14 CFR 61.57(b) starts one hour after sunset, the logging definition of night in 14 CFR 1.1 starts at the end of evening civil twilight (about half an hour after sunset in mid-latitudes, longer in the far north), and the lighting rule of 14 CFR 91.209 starts at sunset itself. Under the rules of the air in Europe and the United Kingdom, night is also civil twilight, while United Kingdom licensing uses half an hour after sunset to half an hour before sunrise. Three landings flown 20 minutes after sunset count for neither the night-currency window nor night logging, yet the aircraft already needs its lights.
Near the poles the answers change shape. In midnight sun there is no sunset and no night under any rule; where the sun sets but never gets 6 degrees below the horizon, lights are required between sunset and sunrise while there is no civil-twilight night at all; in polar night the sun does not rise, so the sunset-to-sunrise window covers the whole day. The readout says which case applies instead of inventing a time.
The converter changes a Zulu time into the airport and your local time, or the other way round: choose which clock the number you type belongs to. It follows daylight saving time and says when a local time does not exist (clocks go forward) or happens twice (clocks go back).
Assumption: this is a planning aid only. Verify the rules and the times with the official sources (the regulation text, the Air Almanac or the authority's own tables) before you rely on them. Sun times follow the NOAA solar equations for a point at sea level and are rounded to the minute, so the almanac can differ by a minute: keep a margin. 14 CFR 61.57(b) is quoted as in the eCFR on 23 October 2026; read it for the exceptions and the aircraft category, class and type conditions. The airport table holds large and medium airports with a four-letter ICAO code and small airports with scheduled service; for any other field use latitude, longitude and its time zone.
Sun position: the NOAA Global Monitoring Laboratory solar calculator equations (after J. Meeus, Astronomical Algorithms): geometric mean longitude and anomaly, eccentricity, equation of centre, apparent longitude, obliquity correction, declination and the equation of time. Hour angle HA = arccos(cos z / (cos latitude × cos declination) − tan latitude × tan declination) with zenith z = 90.833° for sunrise and sunset (refraction 34′ and the sun's radius 16′) and z = 96° for civil twilight (centre of the sun 6° below the horizon); event time = 720 − 4 × (longitude ± HA) − equation of time, minutes from 00:00 UTC. The declination and the equation of time are re-evaluated at the event until it settles. If the argument of the arc cosine is beyond ±1 there is no event that day: the sun stays above (midnight sun, or twilight that never ends) or below (polar night) the chosen elevation.
The windows: each rule is a start event plus an offset and an end event minus an offset — FAA currency (14 CFR 61.57(b)): sunset + 60 min to next sunrise − 60 min; FAA night (14 CFR 1.1) and EASA / UK Rules of the air night (Regulation (EU) No 923/2012, Article 2(97)): end of evening civil twilight to beginning of next morning civil twilight; FAA lights (14 CFR 91.209): sunset to next sunrise; UK Air Navigation Order 2016 Schedule 1 and UK Part-FCL FCL.010: sunset + 30 min to next sunrise − 30 min. The date is the calendar date at the airport. If the offsets leave nothing, or the sun does not get low enough, the readout says so.
Time zones: the airport table holds the IANA zone containing each airport (Intl in the browser applies the rules, so daylight saving time is automatic and no server is used). A local time that falls in a clock change is read with the offset in force before the change (gap) or as the earlier of two (overlap), and the converter says so.
Verified: the sun times were compared with the NOAA calculator's own functions run for 34 airport-days from the equator to 78° N (differences of a few seconds at mid-latitudes), with NOAA's published sunrise and sunset tables, and with the U.S. Naval Observatory's API (sunrise, sunset and civil twilight; within a few minutes, more near the poles where the sun moves almost along the horizon). Polar and no-event cases agree with NOAA on which events exist. The EU, UK and FAA wording was read on the eCFR and on the UK legislation website on 23 October 2026; the EU Aircrew Regulation text of FCL.010 was not read directly (its UK retained form was).
- 14 CFR 61.57(b), night takeoff and landing experience (eCFR, read 23 October 2026) — the period beginning 1 hour after sunset and ending 1 hour before sunrise
- 14 CFR 1.1, definition of night — the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the Air Almanac, converted to local time
- 14 CFR 91.209, aircraft lights — from sunset to sunrise (in Alaska the unlighted-object and 6-degree variant)
- Commission Implementing Regulation (EU) No 923/2012 (SERA), Article 2(97) night, SERA.3215 lights to be displayed by aircraft and SERA.5005(c) VFR at night, as retained in UK law (UK legislation website, read 23 October 2026)
- UK Air Navigation Order 2016, Schedule 1 night, and Commission Regulation (EU) No 1178/2011 Annex I (Part-FCL) FCL.010 Night as retained and amended in UK law — half an hour after sunset to half an hour before sunrise, at surface level
- NOAA Global Monitoring Laboratory, Solar Calculator (equations after J. Meeus, Astronomical Algorithms) — sunrise and sunset at 90.833 degrees zenith, civil twilight at 96 degrees
- OurAirports open data (public domain) for airport positions; IANA time zone database through the browser for local times