A ferry tank is an auxiliary fuel container that is usually temporarily attached to a motorized device which it feeds fuel to. A ferry tanks allows the motor to be used for an extra amount of time than the built specifications. Ferry tanks are typically used in aviation.

In aviation, ferry tanks are commonly used to transport aircraft to destinations beyond the aircraft's specified range

Range (aircraft)

The maximal total range is the distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft....

 and there are no available re-fueling stopover locations. For example, an aircraft with only 1,000 miles range to be delivered from North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 to Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, which is over 2,000 miles away, that aircraft will require a ferry tank to supply it with enough fuel to travel the excess miles.