Why we don’t respect the privacy filter.

When an aircraft's registration goes dark — when the tail resolves to "N/A," or the operator has asked the big tracking sites to hide it — we usually keep tracking it anyway. People ask how we justify that. This is the answer, and the limits we put on it.

Start with what is actually public. ADS-B Out is a transponder system the FAA requires in most controlled airspace. It broadcasts, continuously and unencrypted, the aircraft's 24-bit ICAO address, its position, altitude, speed, and heading. It is unencrypted on purpose: other aircraft and air-traffic control rely on receiving it to keep the sky from colliding with itself. Anyone with a thirty-dollar software-defined radio can hear it from their backyard. This is not a leak or a hack. It is a safety broadcast, transmitted by design, that happens to be legible to anyone standing under the flight path.

The FAA's privacy program, LADD — Limiting Aircraft Data Displayed — does not change any of that. LADD asks operator-facing data services to suppress a given tail from their public listings. It is a request made to the middlemen. It does not touch the broadcast: the aircraft still emits its position, in the clear, exactly as before. And several open data networks — ADSB Exchange, airplanes.live — decline to honor LADD as a matter of policy, because it filters the display, not the signal. So an owner can enroll in LADD, watch their tail vanish from the consumer apps, and still be tracked in full from sources that simply choose to show what the plane is already shouting.

"N/A" registrations are the harder case, and where fingerprinting comes in. Sometimes a jet's ownership is deliberately obscured — held through a shell LLC, re-registered, or stripped of a public owner record. The ICAO hex still broadcasts. What we do is match that persistent hex against the pattern it flies: the home base it returns to, the corridor it repeats, the fleet it moves with, the moment a known tail disappears and a fresh anonymous hex starts flying the identical route out of the identical hangar. None of that is private information. Every piece of it is a public broadcast; we are only declining to forget what we already lawfully received.

The most public demonstration of how thin the "privacy filter" really is came from the owner side. When a well-known operator reportedly spent a large sum re-registering a jet to shake off a college-student tracker, the new registration was matched back to the same airframe within days — because the hex, the base, and the routes had not changed. You cannot spend your way out of a physics broadcast. The re-registration is a paper change; the airplane is still the airplane.

Our argument for publishing is narrow and old: re-publishing information that is already public is protected speech, and there is a genuine public interest in the environmental and civic footprint of the largest private carbon emitters and the most powerful people alive. Courts and regulators have consistently treated the ADS-B stream as public data. We are not surveilling anyone. We are aggregating a signal the aircraft itself transmits to the entire sky.

But "we can" is not "we always should," and the limits matter more than the license. We do not publish the real-time position of aircraft owned by minors. We do not publish live location for aircraft we can identify as chartered for emergency medical, search-and-rescue, or government missions. We do not publish anything where we have specific reason to believe that broadcasting a live location creates a near-term physical-safety risk to a person — in those cases the historical record still gets published, on a delay, because the accountability is in the pattern over time, not in the live dot. And every social cross-post on the platforms that ask for it runs on a 24-hour delay.

The line we draw is between location as spectacle and location as accountability. A billionaire's fifth short hop of the week, six months of a fleet's fuel burn, a politician's off-hours movements during a news cycle they are part of — that is the public record of public figures doing things with public consequences, reconstructed from a public broadcast. Where tracking stops serving accountability and starts serving harm, we stop. Everything between those two points is, we think, exactly what a free press has always been for.