In short
Logged night runs from the end of evening civil twilight to the beginning of morning civil twilight: the sun more than 6° below the horizon. EASA Part-FCL and FAA 14 CFR 1.1 agree.
Sunset to sunrise is longer. The FAA uses it for position lights (14 CFR 91.209), not for the night you log.
UK licences count from half an hour after sunset to half an hour before sunrise.
01 The definition
- EASA Part-FCL defines night as the period between the end of evening civil twilight and the beginning of morning civil twilight. The rule also allows “such other period between sunset and sunrise as may be prescribed by the appropriate authority”: if your national authority prescribes one, check its rule.
- FAA 14 CFR 1.1 uses the same boundaries: the time between the end of evening civil twilight and the beginning of morning civil twilight. For logging night flight time, both use the same −6° standard.
- Civil twilight ends when the centre of the sun is 6° below the horizon. It is dark enough to need lighting, and the horizon is still visible.
02 Three lines, one flight
The same flight gives three different figures depending on the rule. EGLL to KJFK on 21 December 2026, off-blocks 15:00Z, on-blocks 23:00Z, an 8-hour block:
| Rule | Time | Used for |
|---|---|---|
| Night (sun below −6°) | 2:56 | EASA and FAA: the time you log |
| Sunset to sunrise (−0.83°) | 5:46 | FAA 91.209 position lights, not logged |
| UK licence night | 3:38 | For a UK licence: sunset + 30 min to sunrise − 30 min |
Sunset to sunrise uses −0.83°, which allows for refraction and the sun’s radius, as almanacs do.
03 Where it is measured
- The rules do not say where along the route night is measured. The standard practice, and what NightLog Pro does, is to look at the sun from the point below the aircraft, moment by moment, from off-blocks to on-blocks.
- It is measured at surface level. At cruise the horizon dips below the geometric one, so the sun stays visible longer, but that is not the night the rules define. On the same flight, the darkness seen from FL350 lasts 1:41, against 2:56 of logged night.
04 Work it out for your flight
Enter the airports and block times and NightLog Pro gives the −6° night to log, sunset to sunrise and the UK figure, side by side. It runs in your browser and nothing you enter leaves your device.
05 More
- UK licence night: the 30-minute rule
- FAA night currency: 61.57(b) landings
- How accurate is NightLog Pro? The method, checked against the US Naval Observatory, with test flights you can run yourself.