✈️ NightLog Pro Night Flight Time Calculator for EASA & FAA logbooks

NightLog Pro gives a close estimate, not a certified figure. Here is exactly why.

• What we compute: the moments the sun crosses -6° (civil twilight) and -0.83° (sunset/sunrise) along your route, each pinned to the second, using the NOAA solar equations. The night is the exact time between them, rounded to whole minutes once, at the end.
• What we assume: a constant ground speed along the great-circle (shortest) track, no wind, and a surface-level horizon unless you enter a Flight Level.
• Why it can't be exact: your real flight has climb, descent, ATC routing, holding and wind, so your true track and timing differ from the model. Sunrise/sunset times themselves also vary with refraction and terrain.
• How close: the sun itself is not the weak point. Checked against the US Naval Observatory, every sunrise, sunset and civil-twilight time in our test set is within the USNO's own one-minute rounding. What moves the figure is the route: real tracks, winds and climb/descent can shift the crossings by several minutes, more on long or re-routed flights.

The method, a comparison with the US Naval Observatory and test flights you can check yourself: How accurate is NightLog Pro?

Step 1: Enter your flight date in DD-MM-YYYY format
Step 2: Select departure airport and enter Off-Blocks time (UTC)
Step 3: Select arrival airport and enter On-Blocks time (UTC)
Step 4: Press "Calculate Night Time"

NightLog Pro uses Great Circle interpolation to calculate your great-circle flight path, checking the sun every 10 seconds along the route and pinning each crossing to the second.

• NOAA solar equations: the sun's position from the formulas behind NOAA's solar calculator (Meeus, Astronomical Algorithms), checked against the US Naval Observatory
• -6° Threshold: Civil twilight (EASA Part-FCL & FAA 14 CFR 1.1 night)
• -0.83° Threshold: Sunset/sunrise (FAA 14 CFR 91.209 position lights)
• Great-circle path: Constant-speed shortest-path approximation between the two airports

Official sources

• 14 CFR 1.1: definition of "Night"
• 14 CFR 91.209: position lights (sunset to sunrise)
• EASA / SERA: Standardised European Rules of the Air (night definition)

What is "Night" according to EASA Part-FCL?
Night is defined as the period between the end of evening civil twilight and the beginning of morning civil twilight.

What is "Night" according to the FAA?
14 CFR 1.1 defines night using the same civil twilight boundaries as EASA — the period between the end of evening civil twilight and the beginning of morning civil twilight. So for logging night flight time, both regulators use the identical −6° standard.

The FAA adds two further concepts NightLog Pro also flags:

• Position lights (14 CFR 91.209): required from sunset to sunrise (sun at −0.83°), a wider window than civil twilight.
• Night currency (14 CFR 61.57): takeoffs and landings for passenger currency must occur between 1 hour after sunset and 1 hour before sunrise — a separate rule NightLog Pro does not compute.

What is Civil Twilight?
Civil twilight occurs when the sun is 6 degrees below the horizon. At this point:

• It's dark enough that artificial lighting is required
• The horizon is still visible
• This is the regulatory night standard under both EASA Part-FCL and FAA 14 CFR 1.1

• Always verify calculations with your airline's procedures
• This tool assists with EASA Part-FCL and FAA Part 61 requirements
• Keep your official logbook as the primary record
• Use UTC times consistently for accurate calculations

The figure this app gives is the -6° civil-twilight one: EASA Part-FCL and FAA 14 CFR 1.1. The United Kingdom is not on that definition.

• When the UK retained Part-FCL, point FCL.010 was amended to define night as "the time from half an hour after sunset until half an hour before sunrise (both times inclusive), sunset and sunrise being determined at surface level" - the Aviation Safety (Amendment etc.) (EU Exit) Regulations 2019. The same wording is in the Air Navigation Order 2016, Schedule 1.
• Civil twilight ends roughly 30 minutes after sunset at UK latitudes, so the two definitions are close but not equal - and the gap grows in summer and further north. A flight spanning dusk and dawn can differ by half an hour or more.
• NightLog Pro does not compute the UK definition. If you log under a UK licence, read this figure as the EASA/FAA one and work your night out from sunset and sunrise instead - the Airport Solar Data section gives both.

At cruise altitude the visible horizon dips below the geometric horizon. At FL350 the dip is approximately 3.3°. This means the sun stays above your visible horizon longer, so civil twilight and sunset occur later from your perspective. On a flight through twilight the darkness you see can be an hour or more shorter than the night you log (EGLL→KJFK on 21 Dec at FL350: 1:41 instead of 2:56).

Is it required?
No. EASA Part-FCL and FAA 14 CFR 1.1 define night based on surface-level civil twilight, not aircraft altitude. The logged figure is always this surface-level calculation, whatever Flight Level you enter.

Supported Browsers:

• ✅ Chrome / Edge (Recommended)
• ✅ Firefox
• ✅ Safari
• ✅ Mobile browsers (iOS Safari, Chrome Mobile)

Troubleshooting:

• Ensure internet connection for CDN libraries
• All times must be in UTC format
• Type at least 2 characters for airport search

Privacy Policy
Last updated: 1 September 2026 · Full policy

Data We Collect

• NightLog Pro does not collect, store, or transmit any personal data to external servers.
• All flight calculations are performed entirely on your device. No flight data, times, or airport selections leave your device.
• Recent calculations are saved to this device's local storage only. They are never sent anywhere.

Third-Party Services

• This app — calculates entirely offline and contacts no third party. The engine, the airport database and the world map are bundled inside it. It sends one thing: anonymous counts — counter names and whole numbers, never your flights — to NightLog Pro's own server, which you can switch off in Settings.
• The website only — nightlogpro.com loads anonymised performance metrics via Vercel Analytics (no personally identifiable information), and the results map draws its background from CARTO, which receives your IP address as any web server would. The website also keeps anonymous daily totals of its own — how many calculations were run, whether visitors return, which error messages people hit, and thumbs up/down on a result — with no cookie and no identifier of any kind.
• Everything else is self-hosted. Fonts, icons, the mapping library, the astronomical engine and the airport database are all served from nightlogpro.com itself — no other third party sees your visit.
• The Google Play links are ordinary links. Nothing is sent when the page loads. If you follow one, the website counts which of the three links it was, and Google Play opens under Google's privacy policy.

Cookies

• NightLog Pro does not use cookies.