For every point along the flight route, SunSide calculates the real position of the sun (its altitude and direction) at that exact place and time, then compares it to which way the aircraft is pointing. That tells us whether the sun is shining through the left-side or right-side windows at each moment — added up over the whole flight, that gives a shade side (least total sun) and a scenic side (the opposite, where sunrises, sunsets, and dramatic low-angle light happen).

A great circle route is the shortest path between two points on a sphere — for a flight, that means the most direct line between departure and arrival airports, ignoring the actual turns, holding patterns, and airway zig-zags a real aircraft flies. SunSide uses it as an estimate when no real flown track is available yet for a flight. It's a good approximation for the overall sunny/shaded call, but it can miss the temporary side-flips that happen during a real climb-out or approach turn.

These are the three route sources SunSide can use, shown as a banner on your result, from most to least precise:

• Actual flown track — the real maneuvers this exact flight flew, from ADS-B tracking data.
• Representative route — real maneuvers from a recent operation of the same flight number; the sun is still computed fresh for your selected date, and the path barely changes day-to-day for most routes.
• Great circle — an estimated straight-line route, used when no flown track is available yet.

Takeoff and landing usually involve the aircraft turning onto its final heading, which can put the sun on the opposite side than it's on during the steady, straight part of the flight (cruise). SunSide breaks takeoff, cruise, and landing out separately when this matters, so you know if the side you picked for cruise might be reversed for a few minutes during climb-out or approach.

They're always opposite sides of the same seat map. Shade is the side with the least total sun exposure over the flight — best if you want to sleep or avoid glare. Scenic is the side facing the sun — best for sunrise, sunset, and dramatic low-angle light. Pick whichever matches what you actually want from the flight.

Yes — free, no account, no sign-up. Just enter a flight number and date (web app) or let the browser extension read it off the booking page you're already on.

With SunSide web app you can check any flight manually. SunSide browser extension detects flights automatically on the following airline and travel-agency sites, with more being added over time:

No account, no cookies, no tracking identifiers attached to a lookup. Full details are in the privacy policy.