Altiwind shows sunrise, sunset, civil twilight and golden hour for your spot, and flags the hours that fall at night. The times are worked out on your phone with NOAA's solar algorithm, so they're there even without signal. They describe the light, not what you may do in it: for flying in twilight or at night, check your local rules.
What each time means
- Sunrise and sunset: when the top edge of the sun crosses the horizon, allowing for the way the atmosphere bends its light.
- Civil twilight: the sun is up to 6° below the horizon. The sky is still fairly bright, but colours fade, contrast drops and obstacles get harder to judge. There's a stretch before sunrise and another after sunset.
- Golden hour: the sun is less than about 6° above the horizon, just after sunrise and just before sunset. Warm, low light that photographers love, with long shadows and the sun low in your eyes.
- Night: the sun is more than 6° below the horizon. Altiwind flags these hours.
How it feeds the go/no-go score
The daylight check in the go/no-go score uses these times:
| Light | Result |
|---|---|
| Day (sunrise to sunset) | Within your limits |
| Civil twilight | Marginal |
| Night | Outside your limits |
This is about seeing your drone and what's around it, and about the weather that comes with the evening. After sunset the ground cools, the air near the surface calms and the wind at your flying height can pull away from what you feel on the ground. Temperatures fall too, which matters for batteries: see flying drones in cold weather.
Example
London, Thursday 22 October 2026 (BST):
| Morning | Evening | |
|---|---|---|
| Civil twilight | 07:03–07:37 | 17:53–18:27 |
| Sunrise / sunset | 07:37 | 17:53 |
| Golden hour | 07:37–08:24 | 17:06–17:53 |
| Night | until 07:03 | from 18:27 |
Plan an evening flight for the golden hour light and you have from about 17:06 to sunset as "Within your limits" on the daylight check, then 34 minutes of civil twilight marked "Marginal". After 18:27 the hour shows "Outside your limits". Further north and in midsummer, twilight lasts much longer; in winter, flying windows shrink fast. The guide on winter and summer flying windows shows how much.
Computed on your device
The times come from NOAA's solar calculation, based on Jean Meeus's Astronomical Algorithms. NOAA states its sunrise and sunset times are theoretically accurate to within a minute between about 72° north and south (checked October 2026). Because your phone does the maths, your exact position never leaves it; the Altiwind server only ever sees a grid cell about 5 km across.
Real light can differ from the numbers. A hill to the west brings the sun down early in a valley, and thick cloud makes dusk feel darker sooner.
What you get
Sun times and the daylight check for today and the next 24 hours.
FAQ
Does Altiwind tell me whether I can fly at night?
No. Altiwind covers weather and light only. Whether, where and how you can fly in twilight or at night depends on where you are, so check your local rules.
Why do my times differ slightly from another app?
Different apps round differently, use slightly different definitions or a different point for your location. A minute or two either way is normal.
Do the sun times work offline?
Yes. They're calculated on your phone from the date and your position, so they work without signal once the app is installed.
Why is civil twilight marked "Marginal"?
There is still useful light, but less contrast and colour, and it fades quickly. "Marginal" flags it so you plan the end of your flight before it gets dark.