About
A live map of the sky, in three dimensions
Alarium shows aircraft moving across North America as they actually move — at their real altitude, on their real track, right now.
What it does differently
Most flight trackers draw aircraft as symbols on a flat map and put altitude in a panel as a number. Alarium treats altitude as a place. An aircraft is drawn where it is in the air, with a line down to the ground beneath it, so a climb-out, a descent and a holding stack look like what they are.
Positions are smoothed and dead-reckoned between reports rather than jumped, because the feed arrives sparse and out of order and the snapping that causes is what makes a tracker feel cheap.
Where an aircraft came from
About half the traffic here flies under a tail number rather than an airline callsign, and no route database holds a flight plan for those. So Alarium watches instead: an aircraft low over a field, climbing hard, has just departed it. That is not a filing anyone made — it is something observed, and it works the same for a Cessna as for a 737.
Where a filed route does exist, it is checked against the live track before being shown. A filing that the aircraft’s own position contradicts is withheld rather than displayed, because a confident wrong answer is worse than none.
Airports
1,373 airfields, each with its runways, elevation and local time, plus current conditions from the field’s own METAR — including density altitude and the runway the wind favours, which are the two figures pilots reach for and most weather sources omit.
Los Angeles, New York JFK, San Francisco and Denver are good places to start.
What it cannot see
This runs on community ADS-B receivers, and being straightforward about the limits is the only way the rest of the numbers mean anything:
- Aircraft without ADS-B out do not appear at all. Older general aviation is largely invisible here.
- There is no multilateration, so transponders that only reply to radar are missing.
- Coverage varies by place and moment. Movement counts are what Alarium observed, never a complete record of what happened — which is why the airport panel shows rankings, which survive a partial sample, rather than totals, which do not.
- Altitude is barometric, as broadcast. Near the ground on a high-pressure day that can read below the airfield itself.
Sources
- Positions
- ADS-B 1090ES
- Weather
- NWS aviation METAR
- Airfields
- OurAirports
- Basemap
- Mapbox, OpenStreetMap
Alarium is an independent project, not affiliated with any aviation authority, airline or air navigation service provider. It is for interest and education. Do not use it for any operational, navigational or safety purpose.
Who built this
Alarium is designed and built by Brandon Ponce, a product designer — the interface, the rendering, the ingest pipeline and the writing. More work at poncedesign.info and on LinkedIn.
Found something wrong, or want to ask about how a piece of it works? Get in touch.