How to track private jets

What ADS-B is, and how it actually works

ADS-B stands for Automatic Dependent Surveillance — Broadcast. Each word is load-bearing. Automatic: the aircraft transmits without being interrogated by anyone. Dependent: it depends on the aircraft's own navigation kit, normally GPS, rather than on a radar bouncing a pulse off the airframe. Surveillance: the message is a position report. Broadcast: it goes out to everybody, in clear, with no addressing and no encryption.

Roughly twice a second, a transponder equipped for ADS-B Out emits a short message containing its identity, latitude and longitude, barometric and GPS altitude, ground speed, track and vertical rate. In most of the world this travels on 1090 MHz as an Extended Squitter. In the United States, aircraft operating below 18,000 feet may instead use a second link on 978 MHz called UAT — one reason a light aircraft can be visible to an American receiver and invisible to a European one.

Carrying ADS-B Out is not optional. Since 1 January 2020 the FAA has required it in most controlled US airspace, and equivalent European and Australian mandates followed. That mandate is the single reason civilian flight tracking works at all: it converted a patchwork of voluntary transmissions into near universal coverage.

Nobody needs permission to receive it. A receiver is a cheap software-defined radio and an antenna, and thousands of volunteers run them from rooftops and windowsills. Networks such as ADSB Exchange, ADSB.fi and airplanes.live aggregate those feeds into a global picture. Coverage therefore follows population: dense over Western Europe and the US eastern seaboard, thin over the Sahara, and effectively absent over the middle of an ocean, where nobody lives to host a receiver. When an aircraft crosses the North Atlantic it does not stop transmitting — there is simply nothing underneath it listening. Good trackers say so instead of drawing a straight line and pretending.

Older airframes carrying a Mode S transponder but no ADS-B can still be located by multilateration: four or more ground stations time-stamp the same reply and the intersection of those arrival times gives a position. It is coarser than ADS-B and needs dense receiver coverage, so in practice it works over Europe and not much else.

Tail number vs ICAO hex code

Every aircraft carries two identifiers, and confusing them is the most common reason a search comes back empty.

The tail number — properly, the registration — is the alphanumeric string painted on the fuselage or fin: N628TS, G-SUGR, VT-AKV. It is issued by the civil aviation authority of the country the aircraft is registered in, it is a public record in most of those countries, and it changes when the aircraft is sold into a different registry. It is what a human uses.

The ICAO hex code— also called the ICAO 24-bit address, the Mode S address, or just “the hex” — is a 24-bit number written as six hexadecimal characters, for example A835AF. Blocks of addresses are allocated to each country by ICAO and then assigned to individual aircraft by the national registry; every US-registered aircraft has an address beginning with A. Critically, the hex is what is actually inside the radio message. The registration is not transmitted at all — a tracker resolves hex to tail number by looking it up in a registry database.

That indirection is why an aircraft can vanish from a tracker without ever switching off its transponder, and it is exactly the gap the privacy programmes below exploit.

Reading a registration prefix

The first characters of a registration tell you where the aircraft is registered — which is often not where its owner lives. Business aviation makes heavy use of a handful of offshore registries offering favourable tax treatment, straightforward import rules and a shorter paper trail, so a jet flown daily out of London or Dubai may legally be Manx, Maltese or Caymanian.

American registrations are the odd ones out: N is followed by one to five characters with no hyphen, and owners can reserve a specific combination, which is why vanity tails are so much more common in the US fleet. Everywhere else the prefix is separated by a hyphen and the suffix is usually, though not always, allocated sequentially.

Turning a name into a live position

1. Find the registration. This is the hard step and it is a records problem, not a technical one. FAA and other national registries publish owner records; corporate filings, court documents and reporting fill in aircraft held through holding companies. Celebplanes maintains a hand-curated register — start at the roster and open a profile: Cristiano Ronaldo, Mukesh Ambani and Elon Musk each list their registrations, home base and full flight history.
2. Open the aircraft page. Every tracked airframe has one at celebplanes.com/tail/<registration> — for instance LX-GOL or VP-CZM — with its live position, flight history, fuel burn and cumulative CO₂.
3. Watch the map. The live map plots every tracked aircraft at once and colours each by state: airborne, recently moved, or quiet.
4. Read the timestamps. A marker is only as fresh as the last received fix. When an aircraft goes quiet mid-ocean its position is estimated forward from its last known heading and speed — useful, but an estimate, and it should be labelled as one. Treat any tracker that never distinguishes an observed fix from a projected one with suspicion.

Aircraft type matters too, because it determines what a flight can plausibly be. Range, cabin size and hourly cost for every model on the register are on the aircraft pages; a 3,000 nm midsize jet crossing the Atlantic has made a fuel stop whether or not the tracker caught it.

Why some aircraft do not appear

A missing aircraft is not usually evidence of anything interesting. Four explanations cover nearly every case.

FAA PIA — the Privacy ICAO Address programme

PIA lets a US operator flying domestically request a temporary ICAO address that is not associated with its owner in the civil registry, and pair it with a third-party call sign. The aircraft still transmits ADS-B, perfectly normally, at full power — but the hex a tracker receives no longer resolves to the registration, so the flight appears as an anonymous target. This is the single most effective way to disappear from a tracker, and it works because of the hex-to-registration indirection described above. It applies only in US domestic airspace; an aircraft leaving it reverts to its assigned address.

FAA LADD — Limiting Aircraft Data Displayed

LADD is the older and much weaker mechanism. An operator asks the FAA to suppress its aircraft from the data the agency distributes to subscribers, and services that consume that feed honour the request. It does not touch the broadcast, so any network built on independent volunteer receivers — ADSB Exchange and airplanes.live among them — never sees the block in the first place. A LADD-listed aircraft is generally still trackable. More on both in the FAQ and the methodology page.

No receiver in range

ADS-B is line-of-sight. At cruise altitude a ground station hears an aircraft out to roughly 250 nautical miles, and beyond that there is nothing. Oceans, deserts and large stretches of central Asia and Africa have thin or no coverage. Satellite ADS-B receivers exist and close much of the gap for commercial subscribers, but the free public networks are ground-based.

The transponder is off — or the aircraft is not there

Transponders are normally switched off on the ground after shutdown, so a parked jet goes quiet by design. Military and state aircraft are exempt from the civil mandate and many simply do not transmit. And an aircraft can be in a hangar for maintenance for weeks, which looks identical to being hidden.

What is legal, and what the data does not tell you

Tracking aircraft from ADS-B is lawful. The broadcast is unencrypted and mandated, the receiving is passive, and republishing information transmitted in the clear is protected in the United States and permitted in most other jurisdictions. Aircraft registries are public records for the same reason vehicle and property registries are: aircraft operate in shared, publicly administered airspace. News organisations, universities and environmental researchers work from exactly these sources.

What the data does not tell you is who was on board. ADS-B carries a position, not a manifest. A tracked flight shows that a registered airframe went from one place to another at a particular time — nothing more. Private aircraft fly empty on repositioning legs, carry staff and family, and are chartered out when their owners are not using them. Any tracker, headline or social post that states as fact that a named person was aboard a particular flight has gone beyond its evidence.

Celebplanes tracks registered aircraft, not people, and every profile says so. Emissions figures are directional estimates — flight duration multiplied by published fuel burn multiplied by the EPA's 9.57 kg CO₂ per gallon of Jet-A — not audited accounting; real consumption moves by ten to fifteen per cent with payload, routing and weather.

Frequently asked