Rare now means rare here
Our Discord alert channels had turned into a ticker. Yesterday they posted 846 aircraft, roughly one every ninety seconds, and the operator said out loud what the numbers confirmed: even someone who reads everything had stopped reading them.
The volume was the easy half. The uncomfortable half was what the volume consisted of. Over the last twenty-four hours, four types made up 83 per cent of #epic-sky: the A330-300, the 777F, the A330-200 and the 747-400. Three types made up 95 per cent of #sky-alerts: the A350-1000, the 747-8 and the A380. Those are freighters and hub schedules. An Emirates A380 lands in Hamburg on a timetable, and announcing it 95 times a day does not make it rarer.
Meanwhile, on the same night, the network heard an Antonov An-124, a B-25 Mitchell, a Spitfire, a Hurricane, a DC-3, a DC-10, a 747-300, an E-767, a ShinMaywa US-2, a K-MAX and a P-51 Mustang. One airframe each. Not one of them produced a single message. The channel was working exactly backwards.
Why a threshold could not fix it
Three things were broken at once, and none of them was the number.
The rarity came from a column in the restored SkyDex dump, which describes how rare a machine is in the world, and does it badly. We have known since August that the column is inverted in places, with routine widebodies sitting in the top tiers.
The dedup key was the airframe, not the type. Those 272 A330 messages were 272 different tails of one model, which reads as the same message 272 times.
And the volume grew with the network. Between Thursday and Sunday, twenty-one new ADS-B stations joined, and the alert traffic went up eighteenfold, because every new antenna contributes fresh tails of the same common types. That is the part that mattered most: with a fixed tier, the more successful the network gets, the less useful the channel becomes.
Counting what we actually hear
Rarity is now measured by the network itself. For every type we ask a simple question: how many distinct airframes of it have our own receivers heard in the last thirty days? One hull in a month goes to #sky-alerts. Two or three go to #epic-sky. Anything more common stays quiet, however the dump feels about it.
It is the same join that already powers the types wall on every station page, so nothing new is being collected, and it re-measures itself as coverage grows. When a type becomes routine over somebody's new antenna, it crosses the line and leaves the channel on its own. The channel stops growing with the network.
The card now tells you why it exists. Instead of a tier name, it prints the measurement: "one airframe in the last 30 days". You can check that claim against the station pages yourself.
Expect roughly forty-five messages a day per channel instead of eight hundred, and one post per type rather than per tail. The second An-124 of the day is the same news as the first.
Two things did not change. Your collection is untouched: dex rarity, card tiers and XP work exactly as before, because what a catch is worth and what is worth announcing are different questions that happened to share a column. And the curated legends still post with a ping, census or no census. When a Mriya flies, we are not going to be subtle about it.
One honest limit, written down so it does not get lost. We cannot yet say "first time ever on the network", because until today we only stored when an airframe was last heard. From now on we also record when it was first seen. That field will be empty for a while, and we are not going to back-fill it from the data we have, because that would mean claiming a sighting nobody observed. Give it a few weeks and the channels will be able to say it honestly.