One reason that the A380 did not achieve commercial viability for Airbus has been attributed to its extremely large capacity being optimised for a hub-and-spoke system, which was projected by Airbus to be thriving when the programme was conceived. However, airlines underwent a fundamental transition to a point-to-point system, which gets customers to their destination in one flight instead of two or three. The massive scale of the A380 design was able to achieve a very low cost for passenger seat-distance, but efficiency within the hub-and-spoke paradigm was not able to overcome the efficiency of fewer flights required in the point-to-point system. Specifically, US based carriers had been using a multihub strategy, which only justified the need for a handful of VLAs ("very large aircraft" with more than 400 seats) such as the A380, and having too few VLAs meant that they could not achieve economy of scale to spread out the enormous fixed cost of the VLA support infrastructure.