If you ask pilots how they log night time, many will say the same thing: start 30 minutes after sunset, stop 30 minutes before sunrise. It’s easy to remember, easy to teach, and widely used in flight schools.

The trouble is that no major aviation regulator defines night that way. It’s a rule of thumb—not a legal definition. For logbook totals, currency, and ratings, what matters is civil twilight, and that changes with latitude, season, and where you are along your route.

This article explains what “night” really means for logbook purposes, why shortcuts break down, and how accurate night time is calculated on cross-country flights—including what tools like the Pilotflows Night Time Calculator do under the hood.

What regulators actually say

Definitions differ slightly in wording, but the astronomical threshold is the same across most jurisdictions:

AuthorityDefinition (simplified)

FAA (14 CFR §1.1)

Night is 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.

EASA (FCL.010)

Night is the period between the end of evening civil twilight and the beginning of morning civil twilight—or another period between sunset and sunrise as prescribed by the member state.

ICAO (Annex 2)

Same civil-twilight concept used internationally.

Civil twilight ends when the centre of the sun is 6° below the horizon (evening), and begins again when it returns to 6° below the horizon (morning). At that point, the sky is dark enough that unlit ground objects are no longer clearly visible without artificial light—which is why regulators chose this threshold for “night” operations and logging.

Important: This is not the same definition used for passenger night currency under FAA 14 CFR §61.57(b), which uses “one hour after sunset to one hour before sunrise” for takeoffs and landings. Logging night flight time and being current to carry passengers at night are two different questions. See AOPA’s overview of the different “night” definitions for a clear breakdown.

The +30 / −30 myth

The shortcut—“log night from 30 minutes after sunset until 30 minutes before sunrise”—spread because civil twilight often lasts about 30 minutes at mid-latitudes. In many places, on many evenings, the guess is close enough to feel right.

It fails when:

Latitude changes — Near the equator, the sun sets steeply; twilight may be ~20–25 minutes. In northern Europe or Canada, a shallow sunset angle can stretch twilight to 40–50 minutes or more. In high latitudes in summer, the sun may never reach 6° below the horizon; regulatory “night” may not occur at all on that date.
Season changes — The same airport in January vs July can have very different twilight duration.
Direction of travel — Flying west you “chase” daylight; flying east you meet darkness sooner. A fixed offset from departure or arrival times cannot describe what happens in between.

Example (same calendar evening, different latitudes):
On a mid-June date, a late departure from a high-latitude city might still be in twilight long after a pilot applying +30 would start logging night—while a similar clock time near the Mediterranean might align roughly with civil twilight. Same rule of thumb, very different accuracy.

Over hundreds of hours, especially with regular evening flying from northern bases, rule-of-thumb logging can drift by many hours compared to a proper solar calculation—something that can show up when records are reviewed carefully.

Why departure and arrival times alone are not enough

Night is not determined only at your departure or destination aerodrome. It depends on where you are during the flight.

Consider a three-hour leg that starts at dusk:

You may be in daylight at takeoff, enter night mid-route, and land after sunrise at the destination (or the reverse).
A great-circle route at roughly constant groundspeed crosses changing latitudes and longitudes; the sun’s position relative to the horizon changes along the path.

As discussed in community and industry write-ups (e.g. Aviation Stack Exchange on night flight time calculation and MyFlightbook’s notes on sampling GPS along a track), the practical approach is:

Sample points along the route (departure → destination, typically along a great circle).
At each sample, determine whether the sun is more than 6° below the horizon at that location and UTC time.
Sum the time intervals where the condition is “night.”

A single segment defined only by “off-block at A, on-block at B” with no path model will always be an approximation. The more samples along the actual or assumed route, the closer the result.

Tag–night sequences (multiple day/night switches)

On long or high-latitude flights, you can cross the day/night boundary more than once. EASA logbook requirements (FCL.050) expect operating conditions—including night time—to be recorded accurately; total night time is the sum of all night segments on that flight, not one continuous block.

Scenarios where this matters:

Polar or near-polar routes where twilight is prolonged or ambiguous.
Flights from high northern latitudes southward in winter, where you may transition night → day → night again.
Very fast aircraft crossing many degrees of longitude (direction and speed affect how quickly you move relative to the terminator).

Block time (off-block to on-block) is what you log as total time; night time is the portion of that block spent in regulatory night conditions along your path—including taxi if your authority and SOPs count it toward block and you apply the same rules consistently.

Polar twilight and edge cases

Routes that cross the Arctic or Antarctic circles introduce extra complexity:

Polar night and polar twilight can produce long periods where the sun stays near or below the horizon in unusual ways.
“Sunset” and “sunrise” as everyday concepts may not map cleanly to a single daily cycle.
Calculators and logbook tools must use consistent solar algorithms (e.g. sun position libraries) and sensible route sampling—not a fixed minute offset.

For VFR planning, some ANSPs publish civil twilight tables for a reference location (e.g. a national observatory). For logbook night time on a cross-country IFR leg, route-based sampling is the scalable approach.

How to calculate night time in practice

Manual method (conceptual):

Note departure and arrival aerodromes, UTC off-block and on-block times (and arrival date if overnight).
Look up evening civil twilight end and morning civil twilight begin for relevant locations/dates (Air Almanac, reliable aviation apps, or solar calculators).
For a cross-country leg, interpolate position vs time along your route.
Add up minutes where the sun is >6° below the horizon.

Doing this by hand after every flight is tedious and error-prone. That’s why digital logbooks and standalone calculators automate it.

Automated method (what Pilotflows uses):

The Pilotflows Night Time Calculator and the pilot logbook use:

FAA civil twilight — sun more than 6° below the horizon (aligned with 14 CFR §1.1 for US logbook night time).
Departure and arrival airports (ICAO) to anchor the route.
Route sampling between endpoints so cross-country legs aren’t reduced to “night at departure + night at arrival only.”
UTC block times you enter (off-block / on-block), with support for overnight arrivals.

The result is an estimate suitable for logbook reference—always verify against official almanac data and your authority’s requirements for currency and legal purposes.

What you should do as a pilot

Stop teaching +30/−30 as “the definition.” Use it only as a rough planning hint if you must—but log using civil twilight.
Know which “night” applies — logging night time (FCL / §1.1 civil twilight) vs passenger night currency (§61.57(b) one hour after sunset) vs lighting requirements (FAR 91.209 sunset to sunrise).
For cross-countries, use route-aware tools — departure/arrival times plus path sampling, not just “was it dark when I landed?”
Treat the logbook as a legal record — approximations add up; career totals and checkrides deserve defensible numbers.

Summary

Night for logbook purposes (FAA/EASA/ICAO) is tied to civil twilight (sun 6° below the horizon), not “30 minutes after sunset.”
Twilight duration varies with latitude, season, and route.
Accurate night time on a cross-country requires knowing where you were when—not just when you left and arrived.
Multiple night segments on one flight are normal on long or high-latitude legs; total night time is the sum of those segments.

If you want to try a flight before logging it, use the free Night Time Calculator. To log flights with automatic night time in your logbook, create a free Pilotflows account—free up to 150 flight hours, with EASA & FAA fields and route-based night calculation built in.

claims How Night Time Is Actually Calculated (And Why “Sunset + 30 Minutes” Is Wrong)