Aircraft country prefixes: registration prefixes from D- to N explained

An A320 taxis to the runway in a familiar livery, but the tail doesn’t read D- but 9H-. A freighter with an N on the fuselage, a business jet with M-, a regional aircraft with OY- – at the fence you see half a dozen states in a single afternoon. Aircraft country prefixes are the fastest way to bring order to this variety. This guide explains where the prefixes come from, by which rules they are formed, which marks you see most often in Central Europe and why a prefix sometimes just won’t fit the airline.

Country prefix: the short answer

Every civil aircraft carries a registration in two parts: at the front the nationality mark, i.e. the country prefix, followed by the registration mark, which identifies the individual aircraft in the register. In D-AIMA, D is the country prefix for Germany and AIMA is the registration mark. The prefix thus tells you exactly one thing: which state the aircraft is registered in – not which airline it flies for, where it is based or who owns it.

The rules for this are in Annex 7 to the Convention on International Civil Aviation, which ICAO first adopted in 1949. How the complete registration is structured and where it appears on the aircraft is explained in the basics article Understanding aircraft registrations. This one is about the front part.

Where the prefixes come from

Many country prefixes seem arbitrary: HB- for Switzerland, OE- for Austria, EC- for Spain, SX- for Greece. The reason: the prefixes do not come from country names but from radio communications. The International Telecommunication Union (ITU) allocates blocks of callsigns to each state. From the first one or two characters of these blocks, the state chooses its nationality mark and reports it to ICAO. ICAO publishes the reported marks twice a year, in mid-June and mid-December.

This explains a few patterns you will notice while spotting:

• Single-letter prefixes mostly belong to states that received large callsign blocks early on: D (Germany), F (France), G (United Kingdom), I (Italy), N (USA), B (China), C (Canada).
• Two-letter prefixes are the normal case, such as OE, HB, PH, OO, EI, SE or TC.
• Prefixes with a digit such as 9H- (Malta), 9A- (Croatia), 9V- (Singapore) or 4X- (Israel) come from callsign blocks that begin with a digit.
• Several prefixes per state occur: Brazil has PP, PR, PS, PT and PU, Ireland EI and EJ, Portugal CR and CS, Canada C and CF.

The link to radio goes back a long way: even the first nationality marks of 1919 were based on the callsign prefixes of the 1912 radio conference. In scheduled traffic, an aircraft today usually identifies itself with an airline callsign and flight number – the difference is explained in the article Callsign and flight number. In general aviation, by contrast, you often still hear the registration itself on the radio.

The format rules: hyphen, length, characters

According to ICAO Annex 7, registrations are written in capital letters without decoration and with Arabic numerals. A simple rule applies to the hyphen: if the registration mark begins with a letter, a hyphen sits between the prefix and the registration mark. This results in:

Scheme	Example form	What is behind it
Prefix + hyphen + letters	D-ABCD, HB-ABC, OE-ABC, G-ABCD	registration mark begins with a letter, so hyphen
Prefix + digits without hyphen	JA1234, HL1234	registration mark begins with a digit – typical for Japan and South Korea
N + digits/letters	N12345, N123AB	US special case without a hyphen, up to five characters after the N
Prefix + hyphen + digits	e.g. B-1234	some states use a hyphen despite a string of digits

The example forms show the structure, not real aircraft. How long the registration mark is, each state decides itself: Germany, France and the United Kingdom use four letters, Switzerland, Austria and the Netherlands three.

Home turf: D-, OE- and HB-

D- Germany: the prefix with a built-in weight class

The German system is especially rewarding for spotters because the first letter after the D indicates the aircraft class. This is set out in Annex 1 of the Luftverkehrs-Zulassungs-Ordnung (LuftVZO, the German air traffic licensing regulation):

Mark	Class
D-A…	aircraft above 20,000 kg maximum takeoff mass
D-B…	aircraft from 14,000 to 20,000 kg
D-C…	aircraft from 5,700 to 14,000 kg
D-E…	single-engine aircraft up to 2,000 kg
D-F…	single-engine aircraft from 2,000 to 5,700 kg
D-G…	multi-engine aircraft up to 2,000 kg
D-I…	multi-engine aircraft from 2,000 to 5,700 kg
D-H…	rotorcraft (helicopters)
D-K…	motor gliders
D-L…	airships
D-M… / D-N…	sport aircraft with / without engine
D-O…	manned balloons
D-U…	certain unmanned aircraft systems
D-digits	gliders (D plus number)

For everyday life at the fence this means: practically every commercial jet of a German airline carries D-A, whether an Airbus A320neo at Lufthansa, a Boeing 737-800 at TUIfly or a long-haul jet at Condor. Large business jets like the Bombardier Global 7500 are also above 20 tonnes. A Cessna 172, on the other hand, ends up at D-E, a rescue helicopter like the Airbus H145 at D-H. A single-engine turboprop like the Pilatus PC-12 falls into the class D-F.

OE- Austria

Austrian aircraft carry OE- followed by three letters. In scheduled traffic you see the prefix mainly on Austrian Airlines and People’s. At Vienna Airport – for example from the spotters’ hill – OE- is of course the normal case, while in Germany it is more of a splash of color among the D registrations.

HB- Switzerland and Liechtenstein

Switzerland and Liechtenstein share HB-, followed by three letters. According to the ICAO list, each state’s coat of arms is part of the nationality mark for both, and that is exactly how the two states are told apart. At Zurich Airport, for example from observation deck B, HB- dominates thanks to SWISS, Edelweiss and Helvetic Airways. HB- is also frequently seen on business jets in Central Europe.

Europe at a glance: the prefixes you see most often

Almost all of Europe flies into big German airports like Frankfurt or Munich. The following table lists the most important European marks alphabetically and names airlines on whose home register you can expect the prefix:

Prefix	State	Typical airlines on the home register
CS- (also CR-)	Portugal	TAP Air Portugal, Azores Airlines
EC-	Spain	Iberia, Vueling, Air Europa
EI- (also EJ-)	Ireland	Ryanair, Aer Lingus
F-	France	Air France, Transavia France
G-	United Kingdom	British Airways, Virgin Atlantic, Jet2
HA-	Hungary	Wizz Air (Hungarian company)
I-	Italy	ITA Airways, Neos
LN-	Norway	Norwegian, Widerøe
LX-	Luxembourg	Luxair, Cargolux
OH-	Finland	Finnair
OK-	Czech Republic	Smartwings
OO-	Belgium	Brussels Airlines, TUI fly Belgium
OY-	Denmark	Scandinavian traffic, including SAS
PH-	Netherlands	KLM, Transavia, Martinair
SE-	Sweden	SAS
SP-	Poland	LOT, Enter Air
SX-	Greece	Aegean Airlines
TC-	Turkey	Turkish Airlines, Pegasus
TF-	Iceland	Icelandair
YL-	Latvia	airBaltic
9A-	Croatia	Croatia Airlines
9H-	Malta	KM Malta Airlines, Lauda Europe

The airline column describes the home register of the respective company. Individual aircraft can differ, for example with leasing, wet leases or group subsidiaries based in another country. Which airlines belong to which alliance is covered in the comparison Star Alliance, Oneworld and SkyTeam.

Long-haul and cargo: from A6- to N

Long-haul and cargo traffic add prefixes that are missing from the Europe table. The most important ones for spotters in Central Europe:

• A6- – United Arab Emirates, such as Emirates with the A380 and 777-300ER, Etihad and flydubai.
• A7- – Qatar, the prefix of Qatar Airways.
• 9V- – Singapore, at Singapore Airlines.
• B- – China including Hong Kong and Macau. Taiwan also uses B-, followed by digits.
• C- – Canada, in practice usually as C-F… or C-G… at Air Canada, WestJet or Air Transat.
• JA and HL – Japan and South Korea, both with digits and therefore without a hyphen.
• N – the USA, at United, Delta, American and, in cargo traffic, at FedEx, UPS or Atlas Air.

N: the American special case

The US register follows its own rules from the aviation authority FAA. After the N come at most five characters: either digits only, digits with a letter at the end, or digits with two letters at the end. The letters I and O are excluded because they could be confused with 1 and 0, and the first digit may not be zero. The shortest registrations from N1 to N99 are held back by the FAA for internal use. A hyphen is missing entirely – the N goes directly into the digits.

Because the N register is large and open, you come across the prefix away from US airlines too: on business jets, freighters or aircraft registered through US trust arrangements. So an N on the fuselage does not necessarily mean an American airline is behind it.

Special cases spotters should know

Some prefixes show up in Europe more often than the size of the states would suggest:

• 9H- (Malta): Several airline groups run operations in Malta. Accordingly, you often see 9H- on jets whose livery first makes you think of a completely different country.
• VP-B and VQ-B (Bermuda): The register of the British overseas territory is popular for leased aircraft and business jets and was long common with Russian airlines as well.
• M- (Isle of Man) and 2- (Guernsey): Both British Crown dependencies keep their own registers, which mainly show up on business jets. Tips for this clientele are in the guide Spotting business jets.
• VP-, VQ- and ZD-: Other British overseas territories such as the Cayman Islands (VP-C, VQ-C) or Gibraltar (VP-G and ZD-A to ZD-E) have their own marks.
• 4YB: Not a state but a so-called common mark, which ICAO has allocated to an international operating organization.

The most common cause of a “wrong” prefix remains the wet lease, though: an airline rents an aircraft with crew from another operator, and the jet keeps its own registration. How that works and why it happens so often in summer in particular is explained in the article Wet lease explained.

Reading prefixes at the fence: step by step

Important: the prefix of the registration is not the same as the codes used to designate airports and airlines. FRA, EDDF or DLH are IATA and ICAO codes and have nothing to do with the aircraft register – the differences are clarified in the article IATA and ICAO codes explained.

What to keep in mind

• Livery doesn’t beat the prefix. For registration, only the registration counts. Note both, and you will later see which aircraft were operating in foreign colors.
• Registrations move. When an aircraft is sold or transferred to another register, it gets a new registration – sometimes several times over its life. The manufacturer’s serial number, on the other hand, stays the same.
• Military is different. Military aircraft usually do not carry civil registrations but their armed forces’ own markings. What you need to consider there is in the article Photographing military airfields.
• The list is alive. States can report new prefixes. In cases of doubt, the current ICAO list is authoritative, not an older overview from a forum.
• At the fence you stay outside. To get a readable registration you don’t need to get closer than allowed – a longer lens is the better solution. The legal situation is summarized in Is plane spotting allowed?.

Collecting prefixes: a spotting goal of its own

Some spotters collect not just types or airlines but registers: how many nationality marks have you seen so far? At big hubs like Frankfurt you quickly reach an impressive number, especially with freighters and business jets. You can try it out well from the Zeppelinheim viewing platform or the Düsseldorf observation deck. How to keep such lists cleanly is shown in the article Documenting sightings.

Conclusion

The country prefix is the shortest part of the registration and yet the most revealing. It comes from the ITU’s radio callsigns, is listed by ICAO and names the state in which an aircraft is registered. For spotters in Central Europe, D-, OE- and HB- are everyday sights, along with the prefixes of European neighbors and the long-haul states up to the USA’s N. It gets exciting where prefix and livery don’t match – that is exactly where the stories behind a sighting begin.