The aircraft identification (colloquially often incorrectly referred to as aircraft identification or registration ) is an individual alphanumeric code that uniquely identifies an aircraft . In the case of civil aircraft, it is made up of the nationality mark and the national registration mark.
When an aircraft is sold in Germany, the license plate is usually retained. If an aircraft is withdrawn from service or flown in another country under a new number, the number that has become vacant can be reassigned in many countries.
Basis of international law
Article 20 of the Convention on International Civil Aviation of 1944 reads: "Carrying license plates: Every aircraft used in international aviation must carry the nationality and registration marks prescribed for it." (Wording of the translation valid in Germany). The agreement therefore stipulates that every aircraft must be labeled with a unique identification, which is made up of the nationality symbol of the country in which the aircraft is registered and a national registration symbol.
The implementing provisions for Article 20 are set out in Annex 7. According to section 2.3, each state selects its nationality symbol from the letter range that has been assigned to it by the International Telecommunication Union (ITU) for the call signs of its radio stations. The ICAO must be informed of the choice . The registration mark is issued by each state according to its own system. Annex 7 of the agreement also stipulates where and how the license plate must be attached to the aircraft.
The member states of the ICAO are obliged to implement these requirements in their national legislation. As with all provisions of the agreement, these do not apply to state aircraft.
The ICAO regulations go back to the revised Paris Air Transport Agreement of 1932, on which the Chicago Agreement of 1944 is based. It stipulated that the station identification of the on-board radio station of an aircraft should match the aircraft identification.
In the Washington Radio Telephony Agreement of 1927, however, letter ranges were assigned to the countries for the station identification of radio stations. Thus the countries could only choose their aircraft nationality symbols from this area. In addition, it was stipulated in the Washington Agreement that the station identification of the radio station of an aircraft should always consist of five letters. That is why the aircraft registration numbers in many countries still consist of five letters. (The Chicago Convention of 1944 then dropped this provision.)
Assignment of nationality symbols
In the Washington Radio Telephony Agreement of 1927, each country was assigned a range of letters from which it had to take the identifiers of its radio stations. The then great powers USA, Great Britain, France, Italy, Germany and Japan each received a whole block of letters (the USA three), all other countries a part of a letter.
|K, N, W||United States|
|F.||France and colonies|
|I.||Italy and colonies|
|CF ... CK||Canada|
While in some countries the choice of area is obvious (F for France, I for Italy, G for Great Britain), in others, at least at first glance, no connection is discernible; they were probably randomly assigned from the other areas (OO for Belgium, PH for the Netherlands). A conscious choice can be assumed for some countries (Cx for Chile and Canada, Hx for Hungary (Hungaria) and Switzerland (Helvetia)). The assignment is not justified in the agreement itself.
Originally only letters and no numbers were allowed in the identifier. This rule was later changed when many new states emerged in the course of decolonization and letter blocks were no longer available.
The characteristics given here refer to the period since 1955; for the period before that, see German aircraft license plates until 1945 .
Civil, national aircraft registration numbers in Germany consist of the letter "D" for Germany and four digits for gliders and four letters for all other aircraft. The letter following the “D-” categorizes the type or weight of the aircraft. The new labeling system was first introduced on January 18, 1955; it was then changed and added several times:
- until July 1, 1957: aircraft 14–20 t = DA , then DB
- until July 1, 1957: multi-engine aircraft up to 2 t = DE , then DG
- until July 1, 1959: motor glider = DE , then DK
- until 1999: gas and hot air balloons / airships = D name , then DO
- new from July 1, 1957: DF
- new from 1982: DM , DN
The license plate must be affixed on both sides of the aircraft at the tail, and for aircraft up to 5.7 t also on the underside of the left wing. The font must be rich in contrast and at least 30 cm high. The national emblem ( federal flag ) has a minimum height of 15 cm. Similar rules apply to other types of aircraft.
The GDR had the following nationality symbols: 1950–1956 GDR , 1956–1981 DM and 1981–1990 GDR . In 1981/82 there were parallel nationality symbols in the aviation sector of the GDR.
In the Luftwaffe of the Wehrmacht , multi-engine, and in rare cases single-engine, aircraft were given an association number. This was made up of a two-digit alphanumeric squadron identifier to the left of the bar cross and two letters to the right of it, which indicated the position of the aircraft within the squadron. As long as aircraft were not yet assigned to an air force unit, they carried the permanent identification number assigned to them .
German military aircraft of the Bundeswehr have been marked with a numerical system since 1968, which allows conclusions to be drawn about the type and serial number (e.g. 35 + 01, with an iron cross between the numbers). Before this system was introduced, there was a system in which two letters were combined with three digits. The letters stood for the unit to which the aircraft was assigned. The first letter stood for the armed forces and the type of squadron (air force only). The second letter then, in conjunction with the first letter, identified the respective unit or service to which the aircraft was assigned. From the numbers, the allocation of the aircraft to individual squadrons could partly be recognized within the squadron / units.
Military aircraft that have been assigned a civilian registration number after being taken out of service can continue to use the original military registration number as decoration upon special request, but only the civilian registration number is used.
Their design is regulated inand in The nationality symbol "OE" and a hyphen are followed by three letters, the first indicating the type of aircraft. Possible beginnings for a license plate are:
- OE-A, OE-C single-engine, <2,000 kg maximum take-off weight, 1–3 seats
- OE-B aircraft of the federal government (e.g. Federal Ministry of the Interior )
- OE-D, OE-K single-engine, <2,000 kg maximum take-off weight,> 3 seats
- OE-E single-engine, 2,000-5,700 kg maximum take-off weight
- OE-F multi-engine, <5,700 kg maximum take-off weight
- OE-G 5,700–14,000 kg maximum take-off weight
- OE-H 14,000–20,000 kg maximum take-off weight
- OE-I, OE-L > 20,000 kg maximum take-off weight
- OE-U interim permits
- OE-V test registrations
- OE-W watercraft and amphibious vehicles
- OE-X helicopter
- OE-Y unmanned aerial vehicles
An exception to the aircraft registration numbers usually five characters long in Europe are gliders , motorized hang gliders and paragliders , microlights and motor gliders in Austria . In these, the three letters after the hyphen are replaced by four digits and are therefore six characters long. “Round” thousands are not issued (as of Jan. 2013).
- OE-0001 to OE-0999 pure gliders
- OE-1001 to OE-4999 no allocation or allocation known
- OE-5001 to OE-5999 pure gliders
- OE-6001 to OE-6999 motorized hang gliders (syn .: "delta gliders " or "kites" ) and motorized paragliders
- OE-7001 to OE-7999 aerodynamically controlled ultralight aircraft
- OE-8001 to OE-8999 weight- controlled ultralight aircraft (trikes)
- OE-9001 to OE-9999 Motor gliders (TMG), self-launching gliders with auxiliary engines and non-self-launching gliders with return assistance
In Switzerland, the national emblem is officially called the national emblem . It consists of the letters HB and the coat of arms of the Swiss Confederation. The structure and design of the registration number is regulated in the Ordinance on the Registration of Aircraft (VKZ) . For civil aircraft, the registration number consists of the national emblem HB followed by a hyphen and the registration mark. In Switzerland, the official term is aircraft registration . The terms registration and matriculation are also used colloquially .
In the case of airplanes, helicopters, balloons and airships, the registration mark consists of three letters. The first letter of the registration mark contains information about the type of aircraft:
- HB-A twin-engine turboprops from 5.7 to 15 tons, since 2019 also other commercial aircraft (since I and J have been used up)
- HB-B balloons (hot air and gas)
- HB-C single engine Cessna under 5.7 tons (C150 to C210)
- HB-D Other single engines under 5.7 tons
- HB-E On request for Beech and Robin
- HB-F aircraft from Swiss production (Pilatus PC-6, PC-12)
- HB-G twin engines under 5.7 tons (BE45 / 50/55/58/60/65/76/90/10/20, AC60 / 69/85 and others)
- HB-H single-engine aircraft from Swiss production under 5.7 tons (DO27, FFA Bravo, Dätwyler MD, Pilatus PC-7 & PC-9 & PC-21)
- HB-I aircraft over 15 tons (including DC-3 )
- HB-J aircraft over 15 tons when HB-I is depleted (including DC-3)
- HB-K single engine aircraft under 5.7 tons (Beech, Robin, SOCATA, Slingsby, AC12 / 14, Beagle 121)
- HB-L twin - engine aircraft under 5.7 tons (PA23 / 24/30/31/34/42/44/60, P68, BN2, DHC6, C303 / 310/320/335/337/340/401/402/404 / 414, C421 / 425/441)
- HB-M aerobatic aircraft
- HB-N Single-engine Piper under 5.7 tons when HB-P is used up
- HB-O On request for single-engine Piper
- HB-P single-engine Piper under 5.7 tons
- HB-Q balloons when HB-B is used up
- HB-R classic and special
- HB-S Single-motor two-seater under 5.7 tons
- HB-T Single-engine Cessna under 5.7 tons when HB-C is used up
- HB-U single-engine models under 5.7 tons from German, Italian or Eastern Bloc production
- HB-V business jets under 15 tons
- HB-W Ecolight
- HB-X helicopter
- HB-Y Experimental
- HB-Z helicopter when HB-X is used up
- X-HB special identifier. Little used, e.g. B. for the two FFA P-16 X-HB-VAC (formerly military registration J-3004) and X-HB-VAD (previously J-3005).
Gliders and motor gliders are registered with a consecutive number. Motor gliders receive a registration from the range HB-2000 to HB-2999, for pure gliders this area was skipped accordingly. Ecolight motor gliders are assigned to the area above HB-5500. At the beginning of 2009 the counters were at HB-2453, HB-3430 and HB-5505.
The aircraft registration numbers in Switzerland are issued by the Federal Office for Civil Aviation (FOCA). All active aircraft can be queried in the aircraft register (see section Web links).
In 1936 a new designation system was introduced for the then Flugwaffe . A preceding letter gave information about the purpose of the machine. The numbers were again assigned to the machines in groups. For machines that were already in use at that time, the letters were added while keeping the number. Renumbering was rarely done; Renumbering mostly affected the Pilatus P-2 and the machines of the KAB series.
|A.||education||Education and training of pilots|
|B.||bomber||Airplane for ground attacks|
|D.||drone||remote-controlled small aircraft, for example for border surveillance|
|R.||Reconnaissance||Reconnaissance aircraft (e.g. Mirage IIIRS)|
|U||retraining||Transition from a turboprop training aircraft to a fighter aircraft|
|X||Training mock-up||Non-airworthy model to simulate technical faults in the training of maintenance personnel|
These letters are supplemented by a row of two to four digits. Four digits are common for combat aircraft. The first digit indicates the type of aircraft. The next three are for the subtype and the individual aircraft, with the first and second partly for the subtype; and the third and fourth for the single aircraft. Marked as "X" in the following examples: The individual aircraft.
- Mirage IIIBS = J-200x
- Mirage IIIDS = J-201x
- Mirage IIIRS = R-21xx
- Mirage IIIC = J-22xx
- Mirage IIIS = J-23xx
- F-5E = J-30xx (previously used for the FFA P-16 series), the single-seater
- F-5F = J-32xx, the two-seater
- Hawker Hunter J-40xx / 41xx (J-4001 to J-4152)
- Hawker Hunter Trainer J-42xx
In the current fleet, the labeling single-seater and double-seater types F-5 and F / A-18 differs as follows:
- J-3001 to J-3098 are F-5E (single seaters)
- J-3201 to J-3212 are F-5F (two-seater)
- J-5001 to J-5026 are F / A-18C (single seaters)
- J-5231 to J-5238 are F / A-18D (two-seater)
Most aircraft ( Pilatus PC-6 , Pilatus PC-7 , Pilatus PC-9 , Pilatus PC-21 , DA42) and the helicopters (Super Puma, Cougar EC635) have three numbers. These follow a largely similar pattern to the four-digit number.
- PC-6 = V-6xx
- PC-7 = A-9xx
- PC-9 = C-4xx
- PC-21 = A-1xx
Transport aircraft have a "3" for helicopters and a "7" for fixed wing aircraft as the first number.
- Transport aircraft = T-7XX
- Helicopter = T-3xx
History of the national emblem "HB"
Before 1932, the registration number of Swiss aircraft consisted of the national emblem CH (for Confoederatio Helvetica ), followed by a number. When Switzerland joined the revised Paris Aviation Agreement, Switzerland was given the national emblem HB .
On October 13, 1919, an international aviation agreement was passed in Paris by the victorious powers of the Paris Peace Conference. From the point of view of the other countries, it had serious shortcomings, which is why many countries, including Switzerland, did not join. In 1932, the agreement was revised at a conference held in Paris from June 10th to 15th. In addition to the 1919 signatory states, 17 other states, including Switzerland, took part. The revised version was unanimously approved and then ratified by all participating states, except for Persia, which terminated the treaty. The revised agreement came into force on May 17, 1933. Accession to the revised Paris Aviation Agreement was ratified by the Federal Assembly on June 18, 1934 (SR: June 13, NR: June 18). The agreement came into force for Switzerland on October 1, 1934, replaced in 1944 by the agreement on international civil aviation , which - with some revisions - is still in force today.
Annex A of the revised Paris Aviation Agreement states that the radio call sign of an aircraft is identical to its registration number. This in turn should consist of five letters, with the first or the first two letters forming the national emblem. In the International Radio Telegraphy Treaty of Washington of November 25, 1927 , each country was assigned a block of letters for the call signs of its radio stations, which expressly also applied to the radio stations on aircraft. According to this agreement, Switzerland could dispose of the HBA-HBZ block. As a result, the national emblem HB was set for Switzerland in Annex A of the revised Paris Aviation Agreement.
The reason why Switzerland was assigned the callsign HB at the Washington Conference of 1927 is not known. The assumption is that Switzerland wanted a letter block with H like Helvetia , as the second best choice, after the CH, which is common in other areas, was not possible because it was in the letter block of Canada. The assignment is not justified in the contract, nor does the Federal Council's message explain the decision.
- Legends and attempts to explain
There was no blocking of CH by Chile , because in the Washington Radio Telegraphy Treaty of 1927 the letter block CF – CK Canada was assigned, which chose CF as its national emblem. From the block CA – CE allocated to it, Chile chose the national emblem CC.
Another explanation is that HB stands for Helvetian Confederation , but there was never an association with this name. The translation of Confoederatio Helvetica as Helvetic Confederation is historically untenable, as the Latin name was introduced in 1848 at the same time as the German name Swiss Confederation . In addition, it is not plausible that quadrilingual Switzerland should be given a German-language name as a national emblem.
After a caused by fuel shortages ditching a Swissair aircraft in June 1954, jokingly common that HB as a reminder serve for the pilots and for "Hesch Bänzin?" (Do you have gas?) Stand.
Liechtenstein is not an independent ICAO member, but is represented by Switzerland. Accordingly, Liechtenstein aircraft have an HB mark. They differ from Swiss aircraft in that they do not have the Swiss cross as their national emblem, but the small national coat of arms of Liechtenstein , i.e. the gold-red coat of arms of the Liechtenstein Princely House.
US aircraft registration numbers consist of the nationality mark N and a registration mark. In deviation from the ICAO standard, the two parts of the label are not separated by a hyphen.
The registration mark consists of a maximum of 5 characters, whereby the last two characters can be digits as well as letters, the remaining characters can only be digits. The first digit cannot be a zero, the letters cannot be I or O. This registration mark thus deviates from the ICAO standard, according to which the registration mark should consist of 3 or 4 letters, depending on the length of the nationality mark.
The following license plate patterns are therefore possible:
License plate before 1949
Until December 31, 1948, there was an additional letter in front of the actual registration number, which contained information about the aircraft. Since 1949 the license plate no longer contains such a letter. Historic planes still carry it in part, but it no longer appears in the official register.
This letter meant the following:
- C = commercial
- G = glider
- L = limited
- P = private
- R = restricted
- S = state
- X = experimental
For example, the license plate number was the Spirit of St. Louis NX211.
The meaning of N
The nationality mark N goes back to the London Radio Telegraphy Conference of 1912, at which the identifications of the radio stations worldwide were coordinated for the first time. The USA was assigned three letter ranges for the identification of its radio stations: N, W and KDA – KZZ. The Paris Aviation Conference of 1919, at which an internationally uniform scheme for aircraft registration was established for the first time, then adopted this classification.
The reason why these three letter ranges were assigned to the USA in London has not been recorded. The reason why the USA chose the N and not the W or K for its aircraft registration numbers is also not known. The most likely explanation for the N is that in 1912 the U.S. adopted the callsign prefix of the Navy, which was the leader in wireless communications at the time and whose callsigns began with N since 1909.
It is noteworthy that the US adopted the assignment of the 1919 conference even though it did not join the agreement.
The Navy and Marine Corps generally use consecutive serial numbers that have no special meaning. The serial number used by the Air Force since 1923 is now four or five digits (xxxx / xxxxx) and the Navy six digits (xxxxxx), and it appears in full or abbreviated on the tail unit. In the US Air Force the complete license plate contained a prefix before, namely the double-digit fiscal year (fiscal year) of the US government, in which the procurement of the aircraft was decided. There can be several years between the order, construction and finally the first flight. In the US Navy and Marine Corps, the license plate does not allow any conclusions to be drawn about the age of the aircraft. In 1940 the Navy Bureau of Aeronautics began with the five-digit number 00001, and when the five-digit number was used up, the so-called Bureau Number (BuNo) became six-digit.
Exceptions are the Air Force tanker and transport aircraft, which are subordinate to the Air Mobility Command , and the aircraft of the United States Air Forces in Europe . They have a five-digit number on the control unit, of which the first digit represents the last digit of the financial year. The C-17A with "80201" on the tail is aircraft number 08-0201. In the years 1962 to 1965, the Air Force issued more than 10,000 serial numbers (mainly for rockets), which is why both digits of the fiscal year were replaced by the first two digits of the serial number on AMC / USAFE aircraft in order to still form a five-digit number .
The Coast Guard aircraft were numbered consecutively in 1936 with a three-digit consecutive series beginning with V101. In 1945 the V was replaced by a 1, and so the license plates are still four-digit today. Since 1969, the business jets, which are operated by the Coast Guard but are subordinate to the Ministry of Finance, have had their own number plate series starting with 1.
The problem arose with all parts of the US armed forces in the late 1940s and 1950s that many aircraft acquired during the war years were more than 10 years old and still in service. The Fiscal Year was no longer clearly identifiable from the identification numbers attached to the aircraft , and such Air Force aircraft were preceded by "0-". It is a common mistake to read zero as the letter O (for "obsolete").
The aircraft of the US Army are using a yy-xxxxx scheme yy is the last two digits of the fiscal year in which the aircraft was ordered; the numbers xxxxx are attached to the stern. Starting in 1967, the sequence was restarted annually with yy-15000. In 1971 consecutive numbering began with yy-20000. However, a new yy-tt-xxx scheme has been introduced on newer aircraft, with tt representing the type.
Type and the corresponding numbers:
- AH-64 Apache : AH-64D 05, AH-64E 03
- CH-47 Chinook , from the CH-47F model: 08
- UH-60 Black Hawk , from the UH-60M model: 20
- UH-72A Lakota : 72
Air Force: This F-16 has the complete number 79-0403. Today's presentation of the Air Force plate was introduced in 1972.
Air Force: C-17 Globemaster III "The Spirit of Berlin" with the number 60006 (actually 96-0006).
Navy: F / A-18C with the number 164229.
Army: UH-72 Lakota with registration number 11-72198
A Coast Guard MH-65 helicopter, number 6572.
A Coast Guard Gulfstream G550 with registration number 02.
List of nationalities
In the following the list of the nationality symbols of the civil aircraft in a sortable table.
1 The mark of nationality does not conform to Section 2.3 of Annex 7.
2 This contracting state has not registered its nationality mark with the ICAO.
3 This non-contracting state has not registered its nationality mark with the ICAO.
4 Not an ICAO contracting state.
5 Liechtenstein is represented at the ICAO by Switzerland. Accordingly, Liechtenstein aircraft have a Swiss license plate.
Signs of multinational organizations
The ICAO allows several states to jointly run an airline. The license plate area 4YA – 4YZ is reserved for such international operators.
|Signs of multinational operators|
|4YB||Arab Air Cargo (Jordan and Iraq)|
If the operator and the owner are not resident in the same country, the aircraft will be registered in the country of the owner. If both states agree, the flag of the owner state can be drawn on the aircraft instead of the flag of the owner state.
- Russian airplanes are often owned by foreign leasing companies. They then often carry the Russian flag for foreign registration.
Obsolete nationality symbols
|Obsolete nationality symbols|
|YM||Free City of Gdansk||until 1939|
|VR-H||Hong Kong||until 1997 (since then B-)|
|СССР 1||Soviet Union||until 1991 (partly until the mid-1990s)|
|CH||Switzerland||until 1932 (since then HB-)|
1 Cyrillic letters : "SSSR" (Soyuz Sowjetskich Sozialistitscheskich Respublik)
Citizenship mark before 1932
As early as the Paris Aviation Agreement of 1919, a system for identifying aircraft had been laid down, with a mark of nationality followed by a national registration mark. The nationality symbols that had been established by the London Radio Telegraphy Conference of 1913 for the identification of radio stations had been adopted. Of course, this provision was only effective for the contracting states at the time.
The German Empire was an exception. As the loser nation of the First World War, it was simply ignored by the responsible CINA (Convention Internationale portant Réglementation de la Navigation aérienne) when awarding the national emblems . Since the letter "D" was not otherwise assigned by the CINA, it was unauthorized and unauthorized to use it as a national emblem. The following identification mark, to be equated with the registration mark, consisted of an ascending sequence of numbers, starting with the number “1”. However, these license plates used from 1919 onwards were only of a temporary nature; the actual role of the aircraft only became official when the Versailles Treaty entered into force on January 10, 1920. The hyphen itself was used, but was initially not a requirement, so there were also marks with a space or a point between the letter and the number combination. It was not until July 1930 that a horizontal dividing bar became mandatory after reaching a four-digit series of numbers. The license plate was awarded by the Reich Office for Aviation and Motor Vehicles , which could sometimes be done several times, for example if aircraft were badly damaged in emergency landings and therefore temporarily removed from the aircraft role, but were re-approved after successful repairs. The numerical identifier proved to be inexpedient after a while, which is why it was ordered on March 20, 1934 to replace it with a letter code. The aircraft approved before this point in time have been re-registered accordingly. The last known number plate D-3463 was issued in March 1934. An exception was the registration number D-2600 , which was awarded three times and was reserved for Adolf Hitler's personal aircraft and was still in use after 1934.
When the aviation agreement was revised in 1932, the scheme from 1919 for the structure of the number plates was retained. However, the nationality marks were reassigned based on the Washington Radio Telephony Agreement of 1927.
|YM||Gdansk (Free City)|
|AH||Hejaz (western part of today's Saudi Arabia)|
|C numbers, three digits||Colombia|
|XS||Kingdom of Serbia-Croatia-Slovenia|
|N||United States of America|
- FAA Registry - American aircraft registration
- Aircraft Registration Database airframes.org - worldwide, including ICAO24 addresses
- icao.int - Official list of nationalities of the ICAO (PDF)
- Austrian aircraft register of Austro Control
- Helionline.de - German Helicopter Database - Historical documentation of all civil helicopters registered in Germany, supplemented by 20,000 photos (status: 01/2008)
- Overview of the aircraft IDs of the Bundeswehr ( Memento from July 5, 2008 in the Internet Archive ) (old and new system)
- airfleets.net - The history of many aircraft can be traced back using their license plates
- bazl.admin.ch - Swiss aircraft register
- www.luftrecht-online.de ( Memento from March 13, 2014 in the Internet Archive ) German translation of the Chicago Agreement (PDF; 269 kB)
- LuftVZO Annex 1 , accessed on March 11, 2016.
- Peter-Michael Gerhardt: The West German Civil Aircraft Register from 1955. In: Air-Britain Archive March 2014, , p. 2014/009.
- NfL 2-446-19 website DAEC, accessed on April 17, 2019
- 2. DV LuftGerPV laws on the Internet, accessed on April 17, 2019
- Permanent aircraft identification since 1968. In: geschichte.luftwaffe.de. Archived from the original on September 2, 2010 ; Retrieved August 20, 2015 .
- Aircraft identification until 1968. In: geschichte.luftwaffe.de. Archived from the original on September 3, 2010 ; Retrieved August 20, 2015 .
- Swiss translation of the Chicago Agreement , www.admin.ch (PDF file; 206 kB)
- Swiss Ordinance on Aircraft Identification Numbers, www.admin.ch (PDF file; 698 kB)
- AS 1934 p. 645 ff
- Later, Switzerland also received the HEA – HEZ area. For example B. the callsign of the coastal radio station Radio Bern HEB .
- Message No. 2360 of September 17, 1928, published in BBl 1928 II p. 537 ff
- Message of the Federal Council No. 3107 of May 26, 1934, published in BBl 1934 II p. 45 ff.
- Page no longer available , search in web archives: www.bazl.admin.ch TM 02.040-50 of the Federal Office for Civil Aviation
- importance of supplementary letters on aahs-online.org
- What's in an N-Number? ( Memento from December 6, 2010 in the Internet Archive ) at the American Aviation Historical Society at www.aahs-online.org (English)
- Joe Baugher: joebaugher.com (US Air Force), joebaugher.com (US Navy and Marine Corps) and joebaugher.com (Coast Guard)
- AIRCRAFT NATIONALITY MARKS, NATIONAL EMBLEMS AND COMMON MARKS. (PDF, 99.3 kB) ICAO, April 4, 2019, accessed on June 12, 2020 (English).
- Democratic Republic of Timor-Leste: AIP - Aeronautical Information Publication ( Memento of May 22, 2005 in the Internet Archive )
- Karl Ries: Research on the German aircraft role: Part 1: 1919–1934. Dieter Hoffmann, Mainz 1977, ISBN 3-87341-022-2 , p. 4 ff.
- Dave Peel: British Civil Aircraft Registers since 1919 . Earl Shilton, UK: Midland Counties Publications, 1985, ISBN 0-904597-60-1 , p. 276.