A standby alert was a type of alert signal used to prepare a starship against possible threats. It was similar to an intruder alert. The alert could be called by departments, as was the case in 2267 when Captain James T. Kirk put all departments except for weapons on Standby alert when the USS Enterprise was alongside the SS Botany Bay. (TOS: "Space Seed")

Captain Kirk also ordered Lieutenant Hikaru Sulu to place the Enterprise in standby alert when he suspected his starship being invaded by unknown forces. (TOS: "Wink of an Eye")