What is 'Joker Fuel' used for in aviation?

'Joker Fuel' refers to a prebriefed fuel state that is established to ensure that an aircraft has enough fuel to safely transition to the next phase of flight. This concept is crucial for flight operations as it allows pilots to manage fuel consumption effectively while considering additional factors such as route changes, weather considerations, and the requirement for reserves.

By having a defined amount of 'Joker Fuel', pilots can make informed decisions during flight regarding the continuation of their operation or preparation for descent and landing. It acts as a safety net, making sure that pilots can enter the next phase of their mission without risking running low on fuel.

Recognizing this, the other options do not accurately represent the function of 'Joker Fuel'. Emergency fuel is not the same as 'Joker Fuel', since 'Joker Fuel' is typically part of the planned operational fuel management. Likewise, fuel specifically needed to return to base or for extended scenarios addresses different operational needs and does not encompass the prebriefed nature of 'Joker Fuel'.