The network has a front door
For a month the receiver network existed only in pieces. There was a ranking of stations, a page for each receiver, a wall of aircraft types per station, and a recruiting landing on feed.skydex.online with the connector string and the Mac app. What there wasn't was a single page that answered the plain question: what is this thing?
Today there is. skydex.online/adsb is the network's front door. It says in three paragraphs how feeding works. You keep sending to whoever you already send to, and add one more output pointed at us. Then it says what happens to the data afterwards: the aircraft your antenna hears become real traffic in the sky pilots fly through, catches in spotters' collections, and pages for every airframe, type and airline with who heard it and who caught it. Under that, the live numbers: receivers online, distinct aircraft heard in the last 24 hours, countries the stations stand in, the top ten stations by Signal, and the countries the network hears. When a number is unknown, say because the ingest is being rebuilt, the page leaves it out rather than printing a zero. A stranger judging the network by this page should never read "0 receivers online" because of a restart on our side.
We were asked whether this deserved its own subdomain, something like adsb.skydex.online. It doesn't. Search engines treat a subdomain as a mostly separate site: whatever trust the main domain has earned does not flow to it, and skydex.online is young enough that splitting that trust three ways, between the game, the feeder landing and a new host, would have hurt every one of them. So the hub lives on the main domain, linked from every footer, from the station leaderboard and from the feeder landing, and it passes its weight down to the station pages beneath it. The feeder landing stays exactly what it's good at: the setup instructions, the terms, the Mac app, the live map. It got a robots.txt and a sitemap today so it's at least a well-behaved small site of its own.
What our antennas hear over your city
The second change is the one we're more excited about. Every city page on Skydex, the ones with the flying forecast and the visitor feed, now carries a block called Live over {city} when the network has something to say. It's what our own receivers hear within sixty kilometres of that city at this moment: how many aircraft, which types (each one a link to its page), a short list of the nearest flights with altitude and distance, and the number of private aircraft, which are counted but never named.
Nobody else can write that block. Weather sites don't have antennas. Tracking maps have the data but no page per city, and they wouldn't link a Boeing 737 overhead to a collection you can add it to. We can, because it's our data and our pages on both ends.
Two honesty rules hold the block together. It's a snapshot: the network keeps no per-city history of positions, so "right now, as of 12:34 UTC" is the only tense we can use, and the block refreshes itself in your browser. And where the network hears nothing, the block doesn't appear at all. Most cities on Earth have no Skydex receiver yet, and showing seven hundred pages of zeros would tell the world the network is dead, when the truth is that nobody has pointed an antenna at that sky yet. Which, if you live there, is an invitation: feed.skydex.online.
And what it heard over your city this month
The live block answers "right now". A second block, right under it, answers "lately": Heard over {city}, last 30 days, with how many distinct aircraft our receivers picked up within sixty kilometres of the city, on how many days, and which types they were, each type a link. Country pages get the same block for the whole country.
This needed a piece of memory the network didn't have. Until today we knew which station heard which aircraft, but not where the aircraft was, and a station can only be pinned to a city if its owner typed in antenna coordinates. Most never do. Two receivers joined the network this very morning, one in England and one in Canada; the English one has no location set, and under the old scheme it would have counted for nothing on any page. So instead of tying stations to cities, we now roll the sky itself: once a minute the network's live picture is bucketed by where each aircraft actually is, and that history is what the block reads. The English receiver put aircraft over London into it within its first hour, location or not.
The counting unit is the same one the station pages use: an aircraft on a day is one sighting. We don't call them flights, because a receiver can't tell where one flight ends and the next begins, and we say how many of the aircraft we could put a type to, because a list of types that hides its own coverage looks bigger than it is. Private aircraft aren't in this history at all, the same line the live map draws.
And the water, too
Ships got the same treatment on the same day. A city on a coast or a big river now carries On the water near {city}, the vessels the AIS feed sees within sixty kilometres right now, by type, with flag, length, speed and declared destination. Under it sits Seen on the water near {city}, last 30 days: how many distinct vessels, how many days, which types, and which flags they sail under. Country pages get the thirty-day block for the whole coastline.
A footnote about coverage. Our AIS picture is not the whole ocean. The feed is subscribed to a handful of ports we always watch and to the water around wherever a pilot is flying at the moment, so the block appears where people have actually flown or where we seeded coverage, and nowhere else. Fly over a harbour nobody has visited yet and, a day later, its page starts telling the story.
Since the same evening the feed also goes looking on its own. Every city that has a page gets one AIS sample a day, taken between eleven and three by that city's own clock. Harbour traffic is a daytime thing, and a single world-wide snapshot at one instant would catch Europe at lunch and Asia asleep. The sample uses whatever room is left in the subscription after pilots have taken theirs, so nobody flying ever loses coverage to it, and the vessels it finds go into the thirty-day history only: you won't see a ship off Mumbai turn up in your fleet search over Hamburg. Coasts that come back empty twice are checked weekly instead of daily. Yachts and other private craft are counted but never recorded, the same rule the live map has always kept.