Aircraft registrations explained: how to read any tail number

Type identified, airline clear – and then there is still a string of letters on the tail like D-AIFA, HB-JNA or EI-GRJ. For many casual observers, that is the fine print. For spotters, it is the core of the hobby: the registration turns “an A350” into exactly this one aircraft. This guide shows you how to understand and read aircraft registrations, what the letter after the country prefix reveals and why an Irish registration on an Italian leisure airline is not a mistake.

Aircraft registrations: the short answer

An aircraft registration consists of two parts: the nationality mark, which names the country of registry, and the registration mark, which identifies the individual aircraft in that country. In D-AIFA, D stands for Germany and AIFA for the specific aircraft – an Airbus A350-1000 of Lufthansa with the christened name “Deutschland.” On the aircraft there is usually a hyphen between the two parts, while in flight plans the registration is usually written without one.

The international basis is the Chicago Convention of 1944. It requires aircraft in international traffic to carry their registrations and allows registration in only one state at a time. The details are regulated by Annex 7 of the convention, and each country handles the actual issuing itself – in Germany, the Federal Aviation Office (Luftfahrt-Bundesamt) keeps the aircraft register (Luftfahrzeugrolle) for this.

The country prefix: where the aircraft comes from

The nationality marks go back to old radio call sign blocks that were divided up internationally. That is why some prefixes are short and catchy (D for Germany, F for France, G for Great Britain, I for Italy, N for the USA), while others consist of two characters or contain digits. You will run into these prefixes especially often at European airports:

Prefix	Country	Typical example at the airport
D-	Germany	Lufthansa, Condor, Eurowings, TUIfly
OE-	Austria	Austrian Airlines
HB-	Switzerland	SWISS, Edelweiss, Helvetic
EI-	Ireland	Ryanair, Aer Lingus, many leased aircraft
9H-	Malta	Lauda Europe, Malta Air
PH-	Netherlands	KLM, Transavia
OO-	Belgium	Brussels Airlines
G-	Great Britain	British Airways, easyJet UK
F-	France	Air France
A6-	United Arab Emirates	Emirates, Etihad
A7-	Qatar	Qatar Airways
TC-	Turkey	Turkish Airlines, Pegasus

Other prefixes you read regularly in Central Europe: LX- (Luxembourg), OY- (Denmark), SE- (Sweden), LN- (Norway), OH- (Finland), SP- (Poland), OK- (Czech Republic), HA- (Hungary), YL- (Latvia), EC- (Spain), CS- (Portugal), 9V- (Singapore) and C- (Canada). For a detailed overview with memory aids, see the guide to Country codes on aircraft.

The German scheme: what the letter after D- reveals

In Germany, four letters follow the D. The first of them is no coincidence but names the aircraft class by design and maximum permitted takeoff mass. The assignment is in Annex 1 of the Air Traffic Licensing Ordinance (Luftverkehrs-Zulassungs-Ordnung, LuftVZO):

Code	Aircraft class	What you typically see
D-A…	aircraft over 20,000 kg	airliners from A320 to A380, large business jets
D-B…	aircraft 14,000–20,000 kg	smaller regional turboprops such as the ATR 42
D-C…	aircraft 5,700–14,000 kg	mid-size business jets, smaller turboprops
D-E…	single-engine up to 2,000 kg	trainers such as the Cessna 172
D-F…	single-engine 2,000–5,700 kg	single-engine turboprops such as the Pilatus PC-12
D-G…	multi-engine up to 2,000 kg	light twins
D-I…	multi-engine 2,000–5,700 kg	twins and small jets
D-H…	rotorcraft	rescue and police helicopters
D-K…	motor gliders	touring motor gliders at the airfield
D-L…	airships	Zeppelin NT
D-M… / D-N…	powered / unpowered air sports equipment	ultralights (D-M)
D-O…	manned balloons	hot air balloons
D-U…	unmanned aircraft systems	registered drones

Gliders get no class letter but a code number after the D. At a commercial airport you therefore see almost only D-A registrations, while on the Cessna 172 at the flying club it is D-E. A look at the letter after the D therefore sorts an unknown aircraft roughly before you have identified the type.

The airlines’ blocks

Within D-A, three more letters follow, and in practice large airlines often use contiguous blocks. At Lufthansa you can see this clearly: many Airbus aircraft run under D-AI…, such as the A319 D-AILA, the A321neo D-AIEA or the A350-1000 D-AIFA. Many Boeing aircraft, by contrast, carry D-AB…, such as the Boeing 787-9 D-ABPA or the Boeing 747-8 D-ABYT, which was delivered in a retro livery in 2015. Within a block, the registrations often run alphabetically – handy if you want to collect a whole fleet.

A nice detail: registrations are reissued over the decades. At the Technik Museum Speyer stands an older Lufthansa 747 with D-ABYM – the same letter block D-ABY… that Lufthansa later used again for the 747-8. So always note the date and type along with a registration.

Austria, Switzerland, USA: different countries, different systems

The principle is the same everywhere, the details are not. Three systems you constantly meet in the German-speaking region:

• Austria (OE-): The prefix is followed by three letters, the first again naming the class. OE-I and OE-L stand for aircraft over 20 tonnes, which is why the jets of Austrian Airlines carry registrations like OE-LBO or, on the Boeing 777, OE-LP…. Helicopters run under OE-X, gliders and ultralights get four-digit numbers. At the spotters’ hill in Vienna you read OE-L every minute.
• Switzerland (HB-): After HB- come three letters, the first naming the category. Large aircraft over 15 tonnes first ran under HB-I and, once that range was exhausted, under HB-J. That is why SWISS flies with HB-J…: the first Boeing 777-300ER HB-JNA landed in Zurich in January 2016, and the first A220-100 carries HB-JBA. HB-K stands for single-engine and HB-L for twin-engine light aircraft under 5.7 tonnes.
• USA (N): There is no hyphen here. After the N come at most five characters: only digits, or digits with one to two letters at the end. The first digit is never a zero, and I and O are not issued, to avoid confusion with 1 and 0. The numbers N1 to N99 are reserved by the US aviation authority, the FAA, for itself.

In France, F- is followed by four letters; the F-W series is reserved there for prototypes. Great Britain also works with G- and four letters.

Where the registration appears on the aircraft

The LuftVZO prescribes exactly how the registration must look on German aircraft: in block letters, dark on a light background or light on a dark background, permanent and easy to read. On the fuselage of aircraft, the lettering must be at least 30 centimeters high, on wings at least 50 centimeters. In practice, that means for you:

For photos from the deck – for example at the Düsseldorf observation deck or observation deck B in Zurich – it pays to use a focal length that keeps the registration sharply legible on screen later. Which lenses fit is covered in the gear checklist.

Registration, flight number, callsign, hex code: four different things

On flight tracker maps in particular, several identifiers appear side by side. Mixing them up is the most common beginner mistake:

Identifier	Example	Belongs to	Stays the same?
Registration	D-AIFA	the individual aircraft	as long as it is registered in the same country
Flight number	LH 400	the flight in the schedule	changes with every connection
Callsign	DLH400	the flight in radio traffic	changes with every flight
Hex code	six characters, e.g. on the map	the aircraft’s transponder	usually until the country of registry changes

The hex code is the transponder’s 24-bit address. It is also assigned via the country of registry and belongs firmly to the aircraft – which is why you can find a particular aircraft on live maps via registration or hex code, even if it is temporarily flying a different route. How this works technically is explained in the guide to Flight tracking with ADS-B, and the difference between flight number and radio callsign in the article Callsign and flight number. For private aircraft and some business jets, by the way, the callsign is often simply the registration without the hyphen.

Why registrations change

An aircraft does not necessarily keep its registration for life. Typical reasons for a change:

• Sale abroad: The aircraft is deleted from the old register and entered in the new one – a D-A… then becomes, say, an EI- or N registration.
• Move within a group: If an aircraft moves to a subsidiary in another country, the prefix changes too. In the Lufthansa Group, for example, aircraft can switch between German, Austrian and Swiss companies.
• Leasing: Leased aircraft are often registered in countries such as Ireland and re-registered on return or re-lease.
• Personalized registrations: In some countries, especially the US, owners can apply for particular combinations.

For your collection, that means: a re-registered aircraft is technically the same aircraft. In such cases, feel free to note both registrations – that way you later recognize that you have seen this aircraft before. If you want a structured system for this, you will find one in the guide to the Logbook for sightings.

Common mistakes when reading

• Reading the prefix as the operator. EI- means Ireland, not Ryanair. An aircraft with EI- can also fly for Aer Lingus, Neos or a leasing company.
• Forgetting or inventing the hyphen. On the aircraft it says D-AIFA, in databases and flight plans often DAIFA. US registrations never have a hyphen.
• Mixing up 0 and O, 1 and I. For N registrations, the rule that I and O do not occur helps. For European registrations, only a sharp photo helps.
• Noting registrations from memory. Four letters are easily mixed up. A proof photo with a legible registration is the cleanest solution.
• Not cross-checking the type. If the registration you read does not fit the type you see, you probably misread. How to identify types reliably is shown in the guide Identifying aircraft types for beginners.

Spotting with the registration in view is relaxed anywhere you stand legally and close enough. What is allowed around the airport is summarized in Is plane spotting allowed?, and for getting started in the hobby, Plane spotting for beginners helps.

Conclusion

An aircraft registration follows a clear logic: a prefix for the country of registry, followed by the identifier of the individual aircraft. In Germany, the first letter after the D already reveals the class, in Austria and Switzerland it works similarly, and in the US their own rules apply, without a hyphen. If you keep prefix and operator apart, check registrations against the type and add the date, you have a collection that still holds up after re-registrations.