Aviation legislation - REGISTRATION of AIRCRAFT:
All aircraft must be registered in the U.K., before they are permitted to fly. They must also have their allotted registration letters displayed on the airframe in accordance with Article 5 and part ‘B' schedule 2 of the ANO.
The legal requirements in respect of aircraft registration are set out in:
Article 4 of the ANO
Application for registration in the U.K. must be made to the C.A.A on a Form CA1. They will, subject to acceptance of the application, issue a Certificate of Registration. This certificate is valid until there is a change in ownership of the aircraft, or until the aircraft is destroyed or permanently withdrawn from use.
An official list of aircraft registered in the U.K. is kept by the C.A.A. There is also an International Aircraft Register.
An aircraft, other than one permitted to fly without being registered, must not fly in U.K. airspace unless it bears the nationality and registration marks as required by the law of the country in which it is registered.
The national mark of U.K. registered aircraft is the capital letter "G" and the registration mark is a group of four capital letters.
An alternative to the above system is used by aircraft manufacturers/dealers to permit flight test of aircraft without the aircraft being registered. The registrations are not permanent and take the form of capital letter "G" followed by two sets of numerals. The first is allocated to the manufacturer/dealer, the second represents the aircraft itself.
For example, the registration "G-7-161" was allocated to a Slingsby Firefly, (for export to the U.S.A.). The number ‘7' represented the Slingsby Aircraft Company and the ‘161' indicated it was the 161st aircraft of that production order.
A Bae Jetstream aircraft was allocated "G-4-014". The ‘4' in this case being the number allocated to British Aerospace, with the aircraft being the 14th of a batch going to the Sun Air airline.