Has-departed-delay
From FreeSpace Wiki
Has departed delay (Boolean operator) Becomes true <delay> seconds after the specified ship(s) or wing(s) have departed from the mission by warping out. If any ship was destroyed, this operator will never be true. Returns a boolean value; Takes 2 or more arguments: 1: Time delay in seconds (see above). Rest: Name of ship (or wing) we want to check has departed.
Comments
Ships that vanish (ship-vanish) do not count as "departed." Using ship-vanish on a ship that is in a "has-departed-delay" will break the tree (it will never turn "true").