Bort number

In Russian use, the bort number is analogous to the United States' military tail code system and does not provide unique aircraft identification.

On all aircraft except bombers, the bort number is shown on the side of the fuselage, typically near the cockpit.

On bombers the bort number is shown on the vertical stabilizer and nose wheel door.

Unlike the tail code system, bort numbers are not unique to a given aircraft, often change over time, and are not attributable to a certain base or squadron without additional context.

The 3-digit bort number will be replaced by the standard two-digit format if the aircraft is subsequently assigned to an operational unit.

Su-35S displays bort number "07 red"
Tu-95 "21 red" and Tu-160 "10 red" display bort numbers on their nose wheel doors
IL-38N "19 yellow" displays a rare yellow bort number
The fourth Su-57 prototype displays the 3-digit bort number "054 blue"