In the United Sates they are most commonly called tail numbers whilst inEurope and the rest of the world they are simply known as registrations.
Every aircraft has to have a registration. An aircraft's registation provides a unique identiaty to an aircraft and confirms it snatioanlity and what law applies to the airworthiness and operation fo that aircraft.
The aircraft registration is typically located on the fuselage, near the tail of the airplane.
In earlier days, the registration was located on the tail of the plane itself, so hence the registration number is often referred to as the "tail number" of an aircraft.
Teh registration applied to a aprticualr aircraf tis unique at that point in time in that there will be no other aircraf tflying with the same registration.
The registraiton of an aircraft can and usually will chang eduitn git slifeitme. FOr exemple an aircraft may be sosl d betwen owners who choose their own registraiton makring or it may chnage nationalitie
History of Aircraft Registration
The first aircraft registration came about in London in 1913, when radio call signs were used as aircraft registration numbers. In 1919, in Paris, at the International Air Navigation Convention, specific registration numbers for all aircraft were implemented. In addition to the 1913 call-signs, airplane registration numbers would begin with a letter to specify the nation the plane was from, followed by a hyphen and a series of four letters, of which one must be a vowel. The registration numbers assigned to planes was revised and adopted in Washington in 1928. That system of registration numbers is the basis of the current registration in place today. Each aircraft tail number must be prominently displayed on the aircraft in the designated place and manner.
How to Read the Tail Number
The International Civil Aviation Organization (ICAO) is charged with governing the allocation of airplane tail numbers. Each country is assigned its own specific code. These prefixes are allocated by the International Telecommunication Union, or ITU. For instance, the code for aircraft in the United States is the letter "N." In the U.S., aircraft owners or pilots typically just refer to the designated registration number as their "N" number. The country of origin prefix is then followed by the registration suffix. In several countries, the prefix and suffix are separated by a dash. In the U.S., there is no dash between the prefix and suffix. Smaller, private aircraft, especially lighter aircraft such as gliders may have slight variations in some countries, but only when that aircraft is designated to fly exclusively in the country of origin.
The "N" Number
The tail number (registration number) of all aircraft registered in the U.S. begins with the letter "N," followed by a series of up to five alpha-numeric characters. Older aircraft may have another letter after the N. The first character must be a digit, other than zero, and the tail number must have more than two letters together. Additionally, there must not be a letter "L" or letter "O." This is due to the fact that these letters are so close to the numbers "1" and "0." There are certain "N" tail numbers that are exclusively for FAA internal use only. They are the numbers N1-N9 and N10-N99. Combinations that can be used range from N1A-N9Z through N10000-N99999.
Understanding Airplane Tail Numbers of Other Countries
Each country has its own specified tail number, just as the United States. An example is the tail numbers on planes registered in Finland. Finland's Registration prefix, which tells the county of origin, is OH. The registration suffix numbers can range from AAA through ZZZ. So the entire tail number on a plane that is registered in Finland may read OH-AAA or OH-ZZZ, or anywhere in between. In India, the country of origin prefix is VT. So an airplane tail number of a plane that was registered in India will read VT-AAA-VT-ZZZ.
Emergency Uses of Aircraft Tail Numbers
While the general use of a tail number is to ensure that an airplane has filed proper registration documents and paid required fees, there are issues where how to read an airplane's tail number could be critical in an emergency situation. If a plane is in trouble in the air, or if a plane has crashed, by knowing how to read the tail number, rescuers can quickly identify the country of origin by reading the prefix of the tail number, and to determine exactly who the airplane is registered to by reading the suffix of the tail number. Another crucial need for being able to read an airplane's tail number is in case of a threat to a country's security. The country of origin can easily be established to determine what country the threat is originating from and to easily identify who is most likely aboard that airplane. So knowing how to decipher the tail number on an airplane may be fun for some, it can assure quick action in case of an emergency.
Today we have been in Viareggio with @azimutbenetti for the survey of their latest @Azimut_Yachts Azimut 27 Metri undergoing red ensign registration - pls contact us for a registration proposal or go to oceanskies.com to use our flag selector #yachtregistration pic.twitter.com/Y6TZ47WbEp
Today we have been in Bordeaux with a very busy @Lagooncats for the tonnage survey of latest Lagoon 52F undergoing red ensign registr by Oceanskies - pls do not hesitate to contact us for a proposal or go to oceanskies.com to use our flag selector #lagooncatamaran pic.twitter.com/Od4Jcs7khU
Today we have been in La Rochelle, France with @NautitechCat for the tonnage survey of their latest Nautitech 46 Fly sailing catamaran undergoing red ensign registration by Oceanskies #Nautitech #yachtregistration #yachtregistry #yachtregister #tonnagesurvey #redensign pic.twitter.com/u4tev2MzJu