In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.

It is usually painted on both sides of the aircraft , most often in the tail area , although in some cases the serial is painted on the side of the aircraft 's fin / rudder ( s ) .
In air forces , the serial number is used to uniquely identify individual aircraft and is usually painted on both sides of the aircraft fuselage , most often in the tail area , although in some cases the serial is painted on the side of the aircraft 's fin / rudder ( s ) .