Scabbard

Scabbard is the callsign of the Prydwen.

In-game, it is also used to refer to a placeholder NPC who represents an unnamed communications officer of the Brotherhood of Steel stationed at the airship in Fallout 4.

Background
Danse's terminal entries in the Cambridge Police Station stipulate that his team contact Scabbard - more specifically, the Prydwen - should there be unusual activity. Recon Squad Gladius followed orders and attempted to contact Scabbard after Scribe Haylen discovered the Institute's energy readings.

If the Sole Survivor sides with the Railroad and assaults the police station, while flying the Claymore during Rockets' Red Glare, Deacon will hail the Prydwen, with an unnamed communications' engineer, referred to as Scabbard in the subtitles, giving his Vertibird clearance to land on the airship.

Appearances
The Prydwen's callsign is mentioned in Fallout 4, while the character using the name is used during the Rockets' Red Glare quest.