stand by, standby
stand by, standby
ii. A passenger able to board a flight at the last moment provided a seat is available.
iii. In an air defense alert, it means be prepared to take off within the stipulated time (e.g., standby 2 min).
iv. A fallback system if the main one malfunctions (e.g., a standby hydraulic system). Also a duplicated system.
v. As it pertains to flight crew duty and rest periods, it is the period during which a crewmember may be called for duty with minimum notice.