Regulations Reference
Calculate sunrise, sunset, and all three twilight periods for any location and date. Displays FAA night currency windows, UK night definition, and position light requirements. Enter a city name or coordinates — no account required.
Results shown in both UTC and local time — update your UTC offset below
Usage Guide
Four inputs — comprehensive twilight analysis for any location on Earth.
Enter the latitude and longitude of your aerodrome or intended flight area. Positive latitude = North, negative = South. Positive longitude = East, negative = West. Use the quick location buttons for common cities, or find coordinates for your aerodrome from the AIP, Jeppesen charts, or a GPS device. ICAO aerodromes coordinates are listed in their AIP entry.
Select the date of your planned flight. Civil twilight times change significantly through the year — particularly at higher latitudes. For pre-flight planning, check the date of the actual flight. For annual planning, check summer and winter solstices to understand the extremes of your operating environment.
Enter your local time zone offset from UTC — e.g. UTC+1 for UK BST, UTC-5 for US Eastern Standard Time, UTC+10 for AEST. All calculated times are shown in both UTC and local time. Always brief and file in UTC; use local time for scheduling and passenger information only.
The regulatory periods panel shows the exact windows for: FAA position light requirement (sunset to sunrise), FAA night currency period (end of civil twilight to beginning of civil twilight), the 1-hour-before/after window for logging night time, and the UK night definition. Use these times for flight planning, pre-flight briefings, and currency self-assessment.
Twilight Phases
Each twilight phase is defined by the angle of the sun below the horizon and has different visual characteristics and regulatory significance.
After sunset (or before sunrise), the sky is bright enough to carry out normal outdoor activities. The horizon is clearly defined. For FAA purposes, this is the regulatory boundary for passenger-carrying night currency. Navigation lights must already be on (from sunset), but the pilot-in-command needs night currency only after civil twilight ends. Lasts approximately 20–25 minutes at the equator, up to 60+ minutes at high latitudes.
The horizon is just visible to the naked eye. Historically used by navigators for celestial observations (both horizon and bright stars visible simultaneously). No longer regulatory significant for general aviation, but relevant for: maritime operations, astro-navigation training, and understanding why some high-latitude airports operate at what appear to be unusual "night" hours. After nautical twilight, the horizon is no longer usable for celestial navigation.
Any light contribution from the sun to the sky becomes negligible. Professional astronomical observations can begin. Not directly regulatory for aviation, but relevant for understanding when the sky is truly dark for night vision adaptation. The human eye reaches maximum dark adaptation approximately 30–40 minutes after entering complete darkness — well after astronomical twilight ends. Night vision goggles (NVG) performance is optimal after astronomical twilight.
Regulatory Reference
The FAA does not use a single definition of "night" — different regulations reference different time periods. Knowing which applies to which situation prevents currency errors.
The period from 30 minutes before official sunrise to 30 minutes after official sunset. Outside this window, night VFR conditions or IFR rules apply (subject to having the appropriate rating or clearance).
Without a Night Rating (NR), UK/EASA PPL holders may only fly in day VFR conditions. The Night Rating requires 5 hours night flying including 3 hours dual instruction and 5 solo takeoffs and full stop landings at night. Night is defined as end of civil twilight to beginning of civil twilight.
EASA defines night as end of evening civil twilight to beginning of morning civil twilight — consistent with the Air Almanac definition. Commercial licence holders must comply with FCL.050 and operator requirements for night currency.
High Latitude Considerations
Above 60° latitude, the familiar concept of a clear day-night cycle breaks down. Pilots operating in Alaska, Canada, Scandinavia, and similar regions face unique planning challenges.
Above approximately 60.5° latitude, during the summer months the sun may not set below the civil twilight horizon (6° below geometric horizon). This means civil twilight never ends — it is technically daylight (or civil twilight) throughout the 24-hour period.
For pilots, this creates an unusual situation: the FAA night currency period (end of civil twilight to beginning of civil twilight) never occurs. There is no night during which to maintain currency. Pilots based in these regions must either travel to lower latitudes to maintain night currency or understand that their currency will lapse during the midnight sun season without opportunity to renew it locally.
The flip side: at the same high latitudes during winter, the sun may not rise above the astronomical twilight horizon for days or weeks at a time. Operations at airports in northern Alaska, northern Norway, or northern Canada may involve extended periods where VFR flight is not possible due to total darkness — even at midday.
During polar twilight (between astronomical night and civil twilight), low-angle sunlight creates extreme glare conditions when it is present — particularly during what would normally be considered "day" at lower latitudes. Terrain contrast is poor, and conditions can change rapidly as the sun traces a flat arc near the horizon.
Common Questions
Civil twilight is the period after sunset (or before sunrise) when the geometric centre of the sun is between 0° and 6° below the horizon. During civil twilight, there is still enough natural light to clearly distinguish terrestrial objects — the sky is not yet completely dark. For pilots, civil twilight is important for two specific regulatory reasons under FAA rules. First, aircraft position lights (navigation lights) must be turned on during the period from sunset to sunrise. Second, the period one hour after sunset to one hour before sunrise is defined as "night" for instrument currency purposes (recent experience requirements for IFR flight). For passenger-carrying night operations under FAR 61.57, "night" is defined as the period from the end of evening civil twilight to the beginning of morning civil twilight — requiring pilots to have made three takeoffs and landings to a full stop during that specific period in the preceding 90 days.
The FAA defines "night" in two different ways depending on the regulation. For aircraft lighting requirements (14 CFR 91.209) and logging night flight time for currency (14 CFR 61.57b), night is defined as the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the Air Almanac. For pilot certification (logging night flight time in the pilot logbook per 14 CFR 61.51b), night begins one hour after sunset and ends one hour before sunrise. This means a pilot can log night time starting one hour after sunset, but for night currency (the three takeoffs and landings requirement), the operations must be conducted during the more restrictive period — end of evening civil twilight to beginning of morning civil twilight.
The three twilight definitions correspond to the angle of the sun below the horizon. Civil twilight: sun is 0°–6° below the horizon. The sky is still bright enough to see well; civil activities can continue without artificial lighting. This is the most operationally relevant for pilots. Nautical twilight: sun is 6°–12° below the horizon. The horizon is still just visible to the naked eye; it was historically used for maritime celestial navigation to measure star altitudes against the visible horizon. Astronomical twilight: sun is 12°–18° below the horizon. The sky is very dark; professional astronomical observations can begin. Beyond 18° (astronomical night), the sun contributes no illumination to the sky. For pilots, civil twilight is the key threshold. At high latitudes (above 60°N or S), during summer months, the sun may not descend below 6° and civil twilight (or even full daylight) may persist throughout the night.
In the USA, there is no separate night rating — night flying privileges are included in the Private Pilot Certificate after meeting the night flight requirements during training. However, pilots must be night-current to carry passengers at night: three takeoffs and landings to a full stop during the period from end of civil twilight to beginning of civil twilight, within the preceding 90 days, in the same aircraft category and class. Night solo flight during student pilot training requires a specific night endorsement. In the UK and most EASA countries, a Night Rating (NR) is a separate qualification added to the PPL, requiring a minimum of 5 hours of night flight training including 3 hours dual and 1 hour solo cross-country. Without the Night Rating, UK/EASA PPL holders are restricted to flying in day VFR conditions only.
Civil twilight times vary by latitude, longitude, date, and whether standard time or daylight saving time is in effect. The most accurate sources are: the US Naval Observatory (USNO) data services at aa.usno.navy.mil, which provides precise Sun and Moon data for any location and date; aviation apps and EFBs (ForeFlight, Garmin Pilot) which display civil twilight in the flight planning briefing; and the Air Almanac published annually by HMSO/USNO, which is the official reference for civil twilight for aviation regulatory purposes. This calculator uses the NOAA solar calculation algorithm, which is accurate to within 5–10 minutes for most latitudes and dates. For precise legal compliance — particularly for determining exact night currency boundaries — always verify with official sources.
The 30-minute window before sunrise and after sunset does not have specific regulatory significance in FAA regulations, but it is widely used as a practical planning reference. In the UK, Aeronautical Information Publication (AIP) and many operator procedures define this period as an important transition zone for weather minima and lighting. For VFR pilots in the UK, the "day" for purposes of VFR flight is defined as the period from 30 minutes before official sunrise to 30 minutes after official sunset. Outside this period, night VFR or IFR rules apply. During the 30-minute window around sunrise/sunset, visibility can be severely affected by low-angle sun glare directly into the cockpit, which is an underappreciated operational hazard separate from any regulatory definition.
The Air Almanac is a joint publication of the US Naval Observatory (USNO) and Her Majesty's Nautical Almanac Office (HMNAO), published annually. It provides tables of celestial data for aviation use, including: Greenwich Hour Angle (GHA) and declination of the sun, moon, planets, and selected stars at 10-minute intervals throughout the year; sunrise, sunset, civil twilight, and moonrise/moonset tables; and refraction tables. FAA regulations reference the Air Almanac as the authoritative source for civil twilight times used in determining night currency periods. The Air Almanac gives local mean time (LMT) of sunrise and sunset for latitudes from 60°S to 72°N at 5-day intervals, from which pilots can derive the exact civil twilight time for their location.
At the equator, civil twilight lasts approximately 20–25 minutes after sunset throughout the year because the sun sets nearly vertically relative to the horizon. At higher latitudes, the sun sets at a shallower angle, and civil twilight is significantly longer — sometimes lasting over an hour at latitudes above 50°N or S near the solstice. At very high latitudes (above approximately 60° in summer), the sun may not descend below the civil twilight horizon (6°) at all, producing "white nights" or midnight sun conditions where it is never fully dark. For pilots planning night operations near the Arctic or Antarctic circles, the concepts of civil twilight and night take on very different meanings — the normal regulatory definitions may produce situations where "night" never arrives for weeks at a time.
This depends on how "night" is defined for the purpose of the passenger-carrying currency requirement. Under FAA regulations (14 CFR 61.57b), the three takeoffs and landings for passenger-carrying night currency must be performed during the period from the end of evening civil twilight to the beginning of morning civil twilight. If the planned flight with passengers takes place entirely before the end of civil twilight (i.e., at dusk but before full civil twilight ends) it is not night and no night currency is required. However, it is the pilot's responsibility to ensure that if any portion of the flight — including arrival and landing — occurs after the end of civil twilight, night currency must be current for passenger carrying. Departing into an approaching night with uncertainty about arrival time is poor planning if night currency is not current.
Under 14 CFR 91.209, aircraft operating from sunset to sunrise must have position lights (navigation lights) turned on. The regulation specifically references sunset, not the end of civil twilight. This means position lights should be on before civil twilight ends — at the moment of sunset, not when darkness actually falls. Many pilots turn on nav lights slightly before sunset as a conservative practice. The position light requirement is separate from the night currency requirement. An aircraft may fly after sunset with position lights on during civil twilight, with no night currency required for the pilot (if no passengers are carried and the flight ends before civil twilight ends). The order of events in the evening is: sunset → end of civil twilight → end of nautical twilight → end of astronomical twilight → full night.