Tracking an aircraft by registration: how to find any airframe

You have heard that a special livery is operating in your area today, or exactly one aircraft of a fleet is still missing from your hangar. Then searching by flight number does little for you: the aircraft that departs as a flight to Mallorca in the morning may fly to Vienna at noon and to London in the evening. If you want to track an aircraft by registration, you search for the aircraft itself – via its registration or its hex code. This guide shows you how that works on the big services, how to read the history and why some aircraft disappear anyway.

Tracking an aircraft by registration: the short answer

You enter the registration or hex code in a flight tracking service’s search. If the aircraft is in the air and being received, the map jumps straight to it. If it is on the ground, you land on its aircraft page with the latest flights. From this history, you read which routes it flies and can estimate when it will show up at your airport again. For everything else, you set an alert.

The difference between the four identifiers you meet on flight tracker maps is important. Flight number and callsign belong to the flight, registration and hex code belong to the aircraft. The article Callsign and flight number: the difference explains this in detail.

Identifier	Example format	Belongs to	Changes …
Flight number	LH 400	route in the schedule	rarely; the aircraft behind it changes with the rotation
Callsign	DLH400	flight in radio traffic	with every flight
Registration	D-AIXX	aircraft (legally)	when the register changes
Hex code	3Cxxxx	aircraft (transponder)	usually with the register

Registration and hex code: two keys to the same aircraft

The registration is an aircraft’s ID: country prefix plus registration mark, clearly visible on the fuselage or tail. How to read it and what the letter after the D- reveals is in Understanding aircraft registrations. Which prefix belongs to which country is listed in the article on Country codes of aircraft.

The hex code is the fixed 24-bit address of the Mode S transponder. It appears in the signals that ground receivers pick up and is therefore what a flight tracking service actually “sees.” Only a database translates the address into registration, type and operator. The technology behind it is explained in Mode S transponders explained and ICAO 24-bit address (hex code).

The addresses are assigned to states in blocks. This gives a practical rule of thumb for a first look at an unknown code:

Country	Hex range	Typical start
Germany	3C0000 – 3FFFFF	3C, 3D, 3E, 3F
Austria	440000 – 447FFF	440 to 447
Switzerland	4B0000 – 4B7FFF	4B0 to 4B7
Ireland	4CA000 – 4CAFFF	4CA
USA	A00000 – AFFFFF	A

For searching, that means: if you only have the registration, use the registration. If you only have a hex code, for example from your own receiver or a table view, use the hex code. On unfiltered maps, the hex code is often the more reliable route because it does not depend on a database match.

Where to get registrations

• From your own photos: Every sighting with a legible registration is a starting point. If it is blurry, the guide Determining an illegible registration helps.
• From fleet databases: Sites such as Planespotters.net list fleets with registration, type and status. How to use them is described in Using Planespotters.net as a fleet database.
• From official registers: Some countries offer public lookups, others do not. An overview is in Looking up aircraft registers.
• From announcements: Airlines and the spotter community usually name the registration for special liveries. Tips are in Finding special liveries.

Searching on the big services

All the big flight tracking services can search by registration, but they differ in history, filtering policy and extra features.

Flightradar24

On Flightradar24, you type the registration into the search field at the top. The results show you the aircraft; if it is in the air, the map jumps to it, otherwise you land on the overview with the latest flights. Without a subscription, the history goes back seven days, with Silver 90 days, with Gold 365 days and with Business three years. Alerts for a specific registration are available from Silver. A detailed manual is in Flightradar24 step by step, and the subscription tiers are compared in Is a Flightradar24 subscription worth it?.

FlightAware

FlightAware explicitly names two ways to search: the flight identifier and the registration. Via the registration, you get to the history of exactly this aircraft. If the search with a hyphen gets you nowhere, try the spelling without. One detail matters for spotters: for scheduled flights, the registration may be missing in the freely accessible view. FlightAware lists the registrations for airline flights as a feature of the Enterprise account that feeders with their own PiAware receiver get – together with eight months of history. More in the FlightAware guide.

ADS-B Exchange and other tar1090 maps

ADS-B Exchange and many community maps are based on the tar1090 interface. There you can go straight to an aircraft via the address:

• ?icao= followed by the hex code selects exactly this aircraft and hides the others. You separate several codes with commas.
• ?reg= followed by the registration also works; however, the tar1090 documentation recommends the hex code because the search via registration takes longer to load.
• showTrace= with a date in the format YYYY-MM-DD shows the track of a past day – provided the map stores a history.

The advantage of these maps: by their own account, they do not deliberately filter out flights. Which community alternatives exist is compared in Unfiltered community trackers compared.

Criterion	Flightradar24	FlightAware	ADS-B Exchange
Search by registration	yes	yes	yes, also via address parameter
Search by hex code	limited	limited	yes, preferred route
Free history	7 days	limited, more for feeders	individual days via history view
Alerts	from Silver	alerts for departure and arrival	not the focus
Blocked aircraft	partly hidden	details only for owners	no targeted filtering

Reading the history: when does the aircraft come to you?

The real work begins after the search. A single live dot only tells you where the aircraft is right now. The history of the last few days reveals how it is used. Airlines schedule their aircraft in rotations: a short-haul jet often flies several routes back and forth per day, and a long-haul aircraft shuttles between hub and distant destination.

Watch for three things in the history:

• Recurring routes: If your airport shows up several times in the last few days, the chances are good that the aircraft will come back.
• Return to base: Many aircraft end the evening at their home base. From there, the first rotation starts the next morning.
• Pauses: Days without a flight can mean maintenance, standby or storage. Then it is worth checking again later.

Long-haul aircraft are often more rewarding for the targeted hunt than short-haul jets because their rotations are more regular. At hubs such as Frankfurt Airport or Munich Airport, they usually return after the distant destination – the only question is when. How to look up flights further in the past is shown in Looking up an aircraft’s past flights.

Step by step to a targeted sighting

For step 5, a look at Setting up notifications for aircraft, types and airlines is worthwhile. For step 6, you need a spot with a good view of the approaches, in Frankfurt for example the Zeppelinheim viewing platform, in Munich the visitors’ hill (Besucherhügel).

Why some aircraft stay invisible

Not every unsuccessful search is an operating error. There are several reasons why an aircraft appears on no map or only with gaps.

• No coverage: Over oceans, deserts and sparsely populated regions, ground receivers are missing. The track breaks off and resumes later.
• No position: If a transponder sends only Mode S without an ADS-B position, receivers know hex code and altitude but no coordinates. Then only MLAT (multilateration) helps, if enough receivers are in range.
• Blocklists: Owners can have the display restricted on commercial services, in the US for example through the FAA’s LADD program. On FlightAware, the details of blocked aircraft are then visible only to owners or operators.
• Changing addresses: Through the FAA’s PIA program, operators in the US can use an alternative 24-bit address. The aircraft stays visible but can no longer easily be matched to its registration – not even on unfiltered maps.
• Outdated database: After a register change, the match between hex code and registration can lag behind for a while. Then you find the aircraft under the old registration or not at all.

With government and military aircraft in particular, the search quickly reaches its limits. What is realistic there is described in Spotting government aircraft.

Common mistakes in registration searches

• Searching by flight number: Yesterday’s flight number often leads to a different aircraft today. For a specific aircraft, only the registration counts.
• Not varying the spelling: Some searches expect the registration without a hyphen, others with. Try both.
• Confusing live position with arrival: An aircraft near your airport may also just be overflying. Check the destination in the flight details.
• Relying on only one map: If the aircraft is missing on one service, that does not mean it is on the ground.
• Noting old registrations: If an aircraft changes registers, your logbook entry no longer matches the current search. Record the registration at the time of the sighting and add the new one if needed. How to reconcile sightings cleanly afterward is shown in Matching sightings with ADS-B logs.

Getting more out of the registration

The registration is not just a search term but a key to further information. Through fleet databases, you learn type, serial number and delivery date – and with them, how old an aircraft is; the instructions are in Finding out an aircraft’s age. For collectors, the registration is the most important unit anyway: types and airlines repeat, the individual aircraft does not. Anyone who wants to systematically tick off the fleet of the Lufthansa Group, for example, works through the list registration by registration.

Conclusion

You find a specific aircraft not via the flight but via the airframe: by registration on the big services, by hex code on unfiltered maps. The history of the last few days shows you how the aircraft is used and whether the trip to the spot is worth it. Alerts spare you the checking. And if an aircraft does not show up anyway, it is often down to coverage, blocklists or databases – not you.