Today’s long-range aircraft are able to operate on very long intercontinental hauls. Nevertheless, these routes just make up a small part of the actual flown ones. This reserve in range leads to a suboptimal payload-range-efficiency, especially on highly frequented short hauls and compared to those aircraft with a smaller designing range.
The figure shows the payload-range-efficiency as a function of the mission range for different designing ranges. The green graph represents a contemporary long-haul aircraft with a designing range of 12,000 km (~ 6,480 nm). An aircraft with a smaller designing range could operate in an area with a significantly higher PRE.An alternative to utilize the higher efficiency on short hauls is the so called Intermediate Stops Operation. At this, a long haul flight is separated into two or more parts, whereas the aircraft is refuelled at the stopover:
At the same time, the demand for concepts to increase efficiency in air transport comes up further – especially against the backdrop of constant growth which preferably shall proceed carbon-neutral. Operational concepts such as ISO have the distinction of coming with a relatively low technological risk and thus have an advantage over revolutionary technologies concerning costs, time and risk of development. The full potential of ISO can be unlocked by designing airplanes for shorter distances and considering snowball effects by smaller wings and engines. The actual potential of ISO is evaluated at the Institute of Air Transportation Systems. Several issues in the context of ISO have been resolved by a number of publications.