Methodology

How Shadefare works

Shadefare answers one question: which side of the plane will the sun be on during your flight? The answer isn't a rule of thumb — it's geometry. Here is exactly how we compute it.

1. Your route becomes a path over the Earth

From your origin and destination airports we build the flight's ground track. By default that is the great circle — the shortest path over the Earth's surface, which is what aircraft approximately fly on most city pairs. Where we can, we refine it with the actual filed route for that city pair, so doglegs around weather zones, oceanic tracks, and airway routings are reflected in the geometry.

2. The sun's position at every point of the flight

Your local departure time is converted to UTC using the IANA time zone at the origin airport (daylight saving time handled), and the flight duration is estimated from route distance with climb-and-descent overhead. We then sample the aircraft's position roughly every 15 flight minutes, and for each sample compute the sun's azimuth (compass direction) and elevation (height above the horizon) at the aircraft's location and time, using standard solar-position astronomy (the SunCalc algorithms).

3. Sun bearing vs. aircraft heading

At each sample we also know the aircraft's instantaneous heading along the path. The difference between the sun's azimuth and that heading says which side the light falls on: sun to the left of the nose lights the A-side windows, sun to the right lights the other side. (Seat letters start at the left window: seat A is always on the left, facing forward.)

4. Glare weighting

Not all sunlight is equal. A sun sitting 2° above the horizon pours straight through the window; a sun 60° overhead barely grazes it. Each sample is weighted by a glare-intensity function of solar elevation — zero when the sun is below the horizon, strongest at low-to-mid elevations — and the weighted samples are accumulated into a score for each side of the cabin. The side with meaningfully more accumulated glare is the sun side; the other is the shady side. If the whole flight happens in darkness, we tell you it's a night flight and the choice doesn't matter for sun.

What this doesn't capture

• Weather — clouds below or around you can mute everything.
• Exact routing on the day — air traffic control can shift a flight off its usual track.
• Taxi, turns, and holds — the first and last minutes of a flight change heading constantly.

That is why every verdict is a probability-weighted recommendation, not a guarantee — and why we say: sun position calculations are approximate, actual conditions may vary.

Try it

Run your own flight through the sun calculator, or browse pre-computed verdicts for popular routes.

Last updated July 2026