 Ferry tanks are typically used in both civil and military aviation; civil aviation and transport aircraft tend to use internal tanks while combat aircraft will use external tanks.In aviation, ferry tanks allow aircraft additional range to reach destinations beyond the aircraft's specified range when there are no available re-fueling stopover locations.For example, for an aircraft with only 1,000 miles range to be delivered from North America to Hawaii, 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.