'Bingo' is also a tactical brevity code in some Western military air arms which indicates the time at which an aircraft retains just enough fuel to return to its base (RTB) safely. This usually includes a predefined reserve. 'Bingo' or 'Bingo fuel' is a status and a radio call indicating that the caller has reached this point, e.g. "Black Sheep One is Bingo Fuel." It applies to both rotary and fixed-wing aircraft.