# FlightSide — FAQ & How It Works

FlightSide helps you choose which side of the plane to sit on by calculating how the sun moves along your flight route. Enter your departure and arrival to see which side gets direct sunlight and which side stays in cabin shade. No account required. It's free.

Legal details: [Privacy Policy](/privacy) and [Terms Of Use](/terms).

## Using FlightSide

### How do I use FlightSide?

Enter your departure and arrival airports, plus your departure date and time. You can adjust the flight duration if it differs from the estimate.

FlightSide calculates how the sun moves along your route and shows which side of the plane gets more direct sunlight and which side stays in cabin shade.

### Can I share my results?

Yes. Each result includes a shareable link so you can send your sun-on-your-flight analysis to friends or travel companions.

You can also copy the URL directly from your browser or bookmark it to revisit later.

### Is it free? Do you sell my data?

FlightSide is free to use. We do not sell your data, you are not the product.

### Does it work on mobile?

Yes. FlightSide works in any modern mobile browser.

You can search for flights, view the map, and check sun exposure directly from your phone or tablet. No app or account required.

### Does it work without an internet connection?

Yes, mostly. Once the app has loaded, the main tool works fully offline. Airport search, sun calculations, the map, and the seat recommendation all run in your browser with no network needed.

Journal posts you have not opened before will not load until you reconnect. The contact form also requires a connection to send.

For the most reliable offline experience, install FlightSide to your home screen. Look for the install prompt in your browser address bar, or use Add to Home Screen from your browser menu on mobile.

### What timezone should I use for departure?

Use the local time at your departure airport. FlightSide uses that time for all sun calculations and displays the correct arrival time in the destination airport’s timezone below the map.

### How is flight duration estimated?

FlightSide estimates flight duration using the great-circle distance between airports, a typical commercial cruising speed, and a small adjustment for prevailing winds. Eastbound flights get a slight tailwind factor and westbound flights get a headwind factor, which reflects average jet stream conditions over mid-latitudes.

If you know the exact scheduled duration from your booking, you can enter it for more precise sun exposure results.

## Understanding Your Results

### I got a recommended side. Is "left" and "right" from my seat, looking forward?

Yes, from your seat looking toward the front of the plane.

Left means windows on the left side of the cabin. Right means windows on the right side of the cabin.

On many aircraft, left-side windows are often A seats and right-side windows are often J or K seats, but seat letters vary by airline and aircraft type.

### I got a recommended side. What does the "Prefer sun" toggle do?

By default, FlightSide recommends the shadier side to reduce glare on screens and limit heat from direct sun during a flight.

Turn on "Prefer sun" if you want the brighter side instead. Some travelers prefer sunlight for photography, warmth, or watching sunrise or sunset from the air.

### What do the percentages mean?

The percentages show how your entire flight time is distributed between sun through the left-side windows, sun through the right-side windows, daylight ahead or behind the aircraft, and night.

Left + Right + Ahead/behind + Night always add up to 100%.

For example, "70% Sun on left side" means that for 70% of the total flight time, the sun is meaningfully exposed to the left-side windows. "Ahead/behind" means daylight that is mostly forward, rearward, or too glancing to count strongly for either side.

The "Night" percentage shows how much of the flight takes place after sunset or before sunrise, when neither side receives direct sunlight.

### I used another service for the same flight and got a different result. Why?

A few things can explain the difference.

Route modeling: FlightSide models the full great-circle route with high geographic precision. Differences in how each service approximates the path can affect results, especially on long-haul routes that arc far north or south.

Flight duration: if you entered a different duration, or if each service uses a different method to estimate it, the sun calculations will differ. Duration determines where along the route the aircraft is at each moment.

Departure timing: FlightSide shifts calculations slightly forward from the scheduled time to account for typical gate-to-runway time. A service calculating from the exact clock time will produce different sun positions, especially near sunrise or sunset.

Timezones: FlightSide uses airport-based timezones and UTC normalization throughout, avoiding local-device timezone drift.

Solar math and sampling: services can differ in solar algorithms and how frequently they sample along the route, which can flip the recommended side. FlightSide weights each sample by how directly the sun is angled toward the cabin windows. Sun near the nose or tail of the aircraft contributes less than sun broadly angled toward the fuselage.

For flights where the split is close to 50/50, the seat choice does not meaningfully matter regardless of which service you use.

### Why is my result nearly 50/50?

Some routes naturally receive similar sun exposure on both sides.

This often happens on north–south flights, during midday when the sun is high, or on shorter flights where timing limits the difference. In these cases, either side of the cabin may be a reasonable choice.

If glare is a concern and the split is nearly even, an aisle seat may be more comfortable than either window.

### What about night flights?

FlightSide automatically detects when your route is in darkness.

If your entire flight takes place at night, both sides of the cabin will remain shaded and either side works equally well. If only part of your flight is in daylight, only that portion affects the recommendation.

### Why does my westbound flight show so much sun exposure?

Westbound flights "chase" the sun, which can extend daylight significantly.

A westbound evening departure can keep you in sunlight for many hours longer than the same flight eastbound. For example, a 6 pm departure from London to New York may experience sunset conditions for several hours as you travel west at a speed similar to the Earth’s rotation.

FlightSide calculates this extended sun exposure so your seat recommendation reflects the full path of the sun.

### Do equatorial flights show different patterns?

Yes. Near the equator, the sun rises and sets in a way that is closer to vertical compared with higher latitudes. This affects cabin sun exposure in characteristic ways:

- Midday east‑west flights: The sun climbs nearly straight overhead, which often leads to more balanced exposure between the left and right sides. Around the equinoxes, this can result in roughly even splits.

- East‑west flights at other times: The sun may favor one side more strongly depending on season and time of day, but overall exposure tends to be closer to balanced than on similar flights at higher latitudes.

- North‑south flights: Sun exposure is predictable, with morning flights seeing sun on the east side and afternoon flights seeing sun on the west side.

Seasonal effects are smaller near the equator than at higher latitudes, but they still influence the sun’s position and the resulting exposure patterns.

### Why is my tropical flight showing nearly 50/50?

Flights near the equator, especially east-west routes around midday, often show balanced sun exposure.

At the equator, the sun rises quickly in the east, climbs nearly straight overhead, and sets straight in the west. During the overhead period, neither side of the cabin receives strong direct sunlight.

This differs from higher-latitude flights, where the sun stays lower and to one side throughout the day. For tropical midday flights with nearly even splits, an aisle seat may be just as comfortable as either window.

## Choosing Your Seat

### Does seat row matter?

No. FlightSide calculates which side of the aircraft faces the sun, not individual rows.

Whether you sit near the wing or toward the front or back does not significantly change which side receives direct sunlight during a flight.

### What about aisle seats?

You can choose an aisle seat on the recommended side of the aircraft.

Window seats give you more control over the window shade. If avoiding glare or heat from direct sunlight during a flight is important, a window seat on the shaded side offers the most control.

However, if sun exposure is nearly evenly distributed between both sides, an aisle seat may be the more comfortable choice overall.

### Can I choose specific seat numbers?

FlightSide does not assign or sell seats. It tells you which side of the plane is more likely to be sunny or in cabin shade.

You can then choose a specific seat number directly with your airline based on the recommended side.

### What about window tinting?

Modern aircraft windows often have light tinting, but this does not change which side of the cabin faces the sun.

Tinting may reduce brightness slightly, but if your side is in direct sunlight, you will still notice more glare and heat compared to the shaded side.

## Routes & Flight Paths

### Does it work on all aircraft?

Yes. FlightSide determines sun exposure based on the aircraft’s direction of travel, not the specific aircraft model.

As long as the plane is flying from your departure airport to your destination, the left and right sides will be calculated correctly.

### What if my flight path changes?

FlightSide uses a great-circle route between airports, which is the standard shortest path used in aviation planning.

In reality, flights may deviate slightly due to weather, air traffic control, or winds. These differences are usually small and usually do not change which side of the plane faces the sun.

If your departure time changes, simply recalculate the flight to get updated results. You can bookmark or share your results link to revisit or compare different departure times.

### What about layovers?

If your trip includes multiple flight segments, calculate each segment separately.

Sun exposure depends on direction and timing, so each leg of your journey may have a different recommended side.

### Does it work for polar routes?

Yes. Some long-haul flights travel near or over polar regions, especially between North America, Europe, and Asia.

FlightSide calculates sun position based on latitude, longitude, date, and time, so it works at high latitudes as well. Seasonal effects, including very long daylight hours, are automatically factored into the results.

### Do transatlantic and transpacific flights behave differently?

Yes. Transatlantic flights are typically shorter (6–8 hours) and follow relatively direct east-west paths at northern latitudes. The sun stays lower on the horizon, creating clear differences between the left and right sides of the cabin.

Transpacific flights are longer (10–14 hours) and often arc far north over Alaska or the Arctic to follow the great-circle route. This northern routing can make the sun’s position less intuitive. For example, a flight from Seattle to Tokyo might show the sun mostly on the right side even though you are flying "west."

FlightSide automatically accounts for these curved routes when calculating sun exposure along your flight.

### Does weather affect the results?

FlightSide assumes clear skies when calculating sun exposure.

Clouds can reduce brightness and glare, but they do not change which side of the aircraft faces the sun. The recommendation is based on geometry, not weather conditions.

### Can I use this for private jets or small aircraft?

Yes, as long as both airports appear in the search list.

FlightSide calculates sun position based on route direction and time, not airline or aircraft type. However, the airport database primarily includes airports with scheduled commercial service. Private or charter-only airfields may not appear.

## Data & Privacy

### Where does the data come from?

Airports: airport names, coordinates, and timezones come from OurAirports, a public-domain, community-maintained dataset that includes thousands of airports worldwide. FlightSide does not connect to airline systems or booking platforms.

Sun and route calculations: the sun’s position is calculated directly in your browser using standard astronomical formulas. The route is modeled as the great-circle path between the two airports you select.

There is no real-time flight tracking and no third-party flight data involved.

Maps: the map uses MapLibre with a Protomaps-based self-hosted vector style and OpenStreetMap-derived data.

### Is the airport database accurate and up to date?

Airport names, locations, and timezones come from a public-domain dataset that is regularly updated.

The database currently in use was last updated on Sep 9, 2026. You can also check the latest update date at the bottom of the page.

### Why can’t I find my airport?

FlightSide includes airports with scheduled commercial service worldwide.

Some private, military, or charter-only airports may not be listed in the current database.

If you think an airport should be included or something looks incorrect, please [contact us](/contact) and we’ll review it.

### Are heliports and seaplane bases included?

Yes, when they carry scheduled passenger service. Greenland, coastal Alaska, and parts of British Columbia and South Asia depend on helicopters and floatplanes for regular routes, so those bases appear in search alongside airports.

Sun exposure is calculated the same way for them. The split depends on where the sun sits relative to your heading, not on how long you fly, so a short hop can still come out firmly one-sided. What changes is the cabin: in a small aircraft both sides are a seat or two apart, so the choice matters less than it does on an airliner.

Heliports and seaplane bases are only offered in search. They are never suggested as nearby airports or surrounding hubs.

### Do you store my personal information?

No.

FlightSide does not store anything tied to you, and there is no account to attach it to. All calculations are performed in your browser.

FlightSide does keep aggregate usage numbers, such as which routes are popular, but nothing personal.

See our [Privacy Policy](/privacy) for details.

### Do I need an account?

No. There is no account system and no login required.

You can calculate sun exposure for any flight instantly.

### Do you track users?

No.

FlightSide does not use invasive tracking, does not sell user data, and does not build user profiles.

See our [Privacy Policy](/privacy) for details.

### Are you related to Sunflight?

Unaffiliated with Sunflight (sunflight.net, sunflight.org). Similar idea, built differently: FlightSide leads with a seat recommendation, and you still get the full breakdown behind it.

## How It Works

### Does the angle of the sun matter, or just which side it's on?

Yes. FlightSide weights each moment by how directly the sun is angled toward the cabin windows, not just whether it technically falls on the left or right side.

Sun shining nearly straight ahead or behind the aircraft is treated as low side-window exposure. Sun broadly angled toward the fuselage counts as meaningful window sun.

This gives more accurate seat advice on routes where the sun spends long stretches near the nose or tail.

### What is twilight, and does FlightSide model it?

Civil twilight is the period after sunset or before sunrise when the sun is just below the horizon but still lighting the sky. FlightSide models this as a distinct phase separate from full daylight and full night.

Flights that pass through dawn or dusk show twilight in the map overlay and timeline so you can see exactly when conditions shift.

### How does FlightSide calculate sun exposure?

FlightSide models your route as a great-circle path between the two airports, which is the shortest path on the globe. It then samples many points along that path and assigns a time to each point based on your departure time and flight duration.

At each point, FlightSide:

1. Calculates the aircraft’s heading.

2. Computes the sun’s position (azimuth and altitude) at that location and time using standard astronomical formulas.

3. Compares the sun’s direction to the aircraft’s heading to determine whether the sun is on the left side, right side, or below the horizon.

The final percentages represent how much of the total flight time falls into each category: sun on the left, sun on the right, or night.

All calculations are performed in your browser.

### How accurate are the predictions?

The sun’s position is calculated using well-established astronomical formulas, so the solar geometry itself is very accurate.

FlightSide assumes a perfect great-circle route and clear skies. In reality:

- Flights may deviate slightly due to weather or air traffic control.

- Clouds are not modeled.

- During turns, the aircraft heading can differ from the ideal path.

Because of this, the sun calculations are precise, but real-world sunlight exposure can vary slightly depending on routing and conditions.

For most typical commercial flights, the recommendation is directionally very reliable.

### Why not just look at sunrise and sunset times?

Sunrise and sunset times apply to a single location.

Your flight moves across many locations and time zones. The sun’s position relative to the aircraft depends on latitude, longitude, direction of travel, and exact time.

A sunset time at your departure airport does not tell you whether the sun will be on the left or right side halfway through the flight.

FlightSide evaluates the sun’s position at many points along your route and compares it to the aircraft’s heading. That is how it determines cabin shade and direct sunlight during the entire flight, not just at one city.

### Does season matter?

Yes, season affects the sun’s angle and daylight duration, especially at higher latitudes.

FlightSide calculates the sun’s exact position based on date, time, latitude, and longitude. Seasonal changes are automatically factored into the results.

You do not need to adjust anything manually.

### Does altitude matter?

For determining whether the sun is on the left, right, or below the horizon, altitude has only a minor effect compared to direction and time.

FlightSide focuses on route geometry and solar position. While cruising altitude can slightly change how sunlight appears, it does not meaningfully affect which side of the aircraft receives direct sun during a flight.

### Does FlightSide account for departure delays?

Yes. In aviation, "on time" means the aircraft pushes back from the gate within 15 minutes of the scheduled time, not when it actually lifts off. Taxi time from gate to runway adds another 10 to 30 minutes depending on the airport, so even a perfectly on-time flight is often airborne 15 to 40 minutes after the clock time on your ticket.

FlightSide automatically shifts sun calculations forward by a small buffer to better reflect when you are actually in the air.

### What if my flight departs late?

Once your flight details are filled in, a departure delay slider appears next to the Clear button. Use it to shift the sun calculations forward and see how a late departure would affect your seat recommendation.

The displayed departure time, shareable link, and all labels always stay on your scheduled time. Only the internal sun calculations use the adjusted time.