Study the following.
When establishing communication an aircraft shall use the full callsigns of both stations. After satisfactory communication has been established and provided that no confusion is likely to occur, the ground station may abbreviate callsigns (see the table below). A pilot may only abbreviate the callsign of his aircraft if it has first been abbreviated by the aeronautical ground station.
| Type | Example | |
| Full | Abbreviated | |
| a) the characters corresponding to the registration marking of the aircraft; | G-ABCD Cessna G-ABCD | G-CD Cessna G-CD |
| b) the telephony designator of the aircraft operating agency, followed by the last four characters of the registration marking of the aircraft; or | FASTAIR DCAB | FASTAIR AB |
| c) the telephony designator of the aircraft operating agency, followed by the flight identification | FASTAIR 345 | No abbreviated form |
Note: the name of the aircraft manufacturer or name of aircraft model may be used as a radiotelephony prefix to the Type a) above.