How Jetorama works

Aircraft positions

Every airliner carries a transponder that broadcasts ADS-B messages: its unique address, callsign, position from GPS, altitude, speed, heading and vertical rate, several times a second. Anyone with a small receiver can pick these up, and tens of thousands of volunteers do, feeding them into community networks such as adsb.lol and adsb.fi. Jetorama asks those networks for every aircraft within a few miles of the airport you are watching, a few times a minute, through its own small proxy so the community feeds are never overloaded.

Between updates, Jetorama interpolates. Each aircraft's last two positions, heading and speed are used to keep it moving smoothly toward where it should be, easing onto each new fix as it arrives. If a fix is late, the aircraft coasts briefly on its last known track rather than freezing; if it is very late, the aircraft fades out.

What each aircraft is doing

The feed says where an aircraft is, not what it is doing, so Jetorama works that out. Altitude above the field, ground speed, vertical rate and position relative to the runways decide whether an aircraft is on final approach, landing, rolling out, taxiing, parked at a gate, holding, taking off or climbing away. Those phases drive the animation: gear comes down on approach, the strobes flash on the runway, the aircraft turns onto the taxiway centreline, and the ground crew appears when it reaches a stand.

The same evidence decides which runway ends are in use. Each landing and each departure roll is recorded per runway, and the runway lights, the green threshold bars and the approach strobes, move to match. When traffic is quiet the airport's usual flow is assumed until the next aircraft proves otherwise.

The airport itself

Runways, taxiways, aprons, terminals, hangars, gate stands, people movers, towers and the surrounding buildings and roads are drawn from OpenStreetMap, the openly licensed map of the world, and rebuilt whenever the data improves. Runway lengths and displaced thresholds are checked against each airport's published data. Terrain comes from open elevation models, and coastlines and water from OpenStreetMap's coastline data, so the ocean is where the ocean is.

Each airport is rendered by one of two engines: a 2D scene that draws the Diorama, Arcade and Neon looks, and a 3D scene for the Modern flyover with real relief, extruded buildings and modelled aircraft with working lights.

Light, weather and the globe

The sun's position over each airport is calculated from the time and the airport's coordinates, so dawn, dusk and night arrive when they really do, and the field's lighting comes up after sunset. Weather comes from each airport's METAR, the coded observation its own station publishes every half hour or so, via the US National Weather Service's Aviation Weather Center: sky cover, precipitation, wind and gusts.

The home-screen globe uses NASA's Global Imagery Browse Services. The satellite look is the VIIRS true-colour composite from two days ago, the most recent full day, with NASA's city-lights layer on the night side. The Diorama look paints NASA's cloud-free Blue Marble in the map's palette, adds the same day's clouds, and shows where it is raining right now from the GPM IMERG rain-rate product, updated every half hour.

Routes and airlines

A flight's callsign identifies the airline and flight number, and community route databases record where each flight number usually goes. Jetorama matches the two and checks the answer against the aircraft's actual position and direction, so a flight that is clearly heading somewhere else is shown without a route rather than with the wrong one. Airline names and logos come from open airline databases.

What Jetorama does not do

It does not track people. There are no accounts, no sign-in and no personal data; the only thing stored on your device is your choice of airport and look. It is not a source for operational decisions: coverage has gaps, data can be seconds to minutes old, and phases are inferred. It is a way to watch, and to understand, how an airport breathes.