✈️ NightLog Pro

Night-time calculator for EASA Part-FCL & FAA logbooks

Flight Date
Enter date as two-digit day, two-digit month, four-digit year
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Departure
Arrival
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Airport Solar Data
🛫 DEP
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Dawn (-6°) --:--
Sunrise --:--
Sunset --:--
Dusk (-6°) --:--
🛬 ARR
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Dawn (-6°) --:--
Sunrise --:--
Sunset --:--
Dusk (-6°) --:--
Flight Timeline
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Night (-6°)
Twilight
Day
Solar Intercept Map
Twilight shade (−0.83° to −6°)
Night shade (below −6°)
Shading is the sky at one instant (the crossing time); markers are where your route crossed each threshold.Why aren't the markers exactly on the shading edge?Picture night as a giant shadow that sweeps slowly across the Earth as it spins — like a curtain being drawn closed.

The shaded area is a single photo of that curtain, frozen at one instant. But your aircraft crossed each line (−0.83° and −6°) at slightly different times, and the curtain kept moving in between. So a marker for a line crossed a little earlier or later can sit just beside the frozen edge, not exactly on it.

Nothing is wrong: your crossing times and the night total stay accurate. A single snapshot simply can't hold two moments at once.
How was this calculated?
Estimate NightLog Pro models your flight as a constant-speed great-circle path and checks the sun's position each minute. Real routing, winds and climb/descent shift the actual crossings by a few minutes. Your official logbook remains the record of authority.
Flight Manifest
Awaiting Calculation Enter flight details and calculate to view manifest.
Help & Documentation
NightLog Pro gives a close estimate, not a certified figure. Here is exactly why.
  • What we compute: the exact moments the sun crosses -6° (civil twilight) and -0.83° (sunset/sunrise) at positions sampled once per minute, using the SunCalc astronomical model.
  • 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: for normal routings the threshold crossings are typically within a few minutes; deviations grow on heavily re-routed or high-latitude flights.
⚠️ Use NightLog Pro to estimate and cross-check. Your official logbook and your operator's procedures remain the record of authority.
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: Click "Calculate Night Time"

💡 Tip: All times must be in UTC. The app handles midnight crossings automatically.
NightLog Pro uses Great Circle interpolation to calculate your great-circle flight path, sampling your position every 1 minute along the route.
  • SunCalc Library: Established astronomical model for sun position
  • -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
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
⚠️ This is an estimate. Positions are sampled every minute along a constant-speed great-circle path. Real routing, winds and climb/descent will move the actual crossings by a few minutes. Always reconcile against your official logbook.
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 slightly longer, so civil twilight and sunset occur later from your perspective, shortening the calculated night time.

Is it required?
No. EASA Part-FCL and FAA 14 CFR 1.1 define night based on surface-level civil twilight, not aircraft altitude. For regulatory logbook purposes, leave Flight Level blank. The standard calculation is what your authority expects.
💡 Enter a Flight Level only if you want a physically accurate estimate of darkness at cruise altitude. It does not change your regulatory night time obligation.
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: June 2026

Data We Collect
  • NightLog Pro does not collect, store, or transmit any personal data to external servers.
  • All flight calculations are performed entirely in your browser. No flight data, times, or airport selections leave your device.
  • Recent calculations are saved to your browser's localStorage only. This data stays on your device and is never sent anywhere.
Third-Party Services
  • Vercel Analytics & Speed Insights — collects anonymised performance metrics (page load times, Web Vitals) with no personally identifiable information. See Vercel's Privacy Policy.
  • CDN Libraries (SunCalc, Leaflet, Lucide, Google Fonts) — loaded from public CDNs. These providers may log standard server request data (IP, timestamp) per their own policies.
  • Airport Database — fetched from a public GitHub repository. No personal data is included in this request.
Cookies
  • NightLog Pro does not use cookies.
📬 Contact & Enquiries
For questions, feedback, or privacy concerns, please reach out at:
slimiedu@gmail.com