Flexibility within flight operations as an evaluation criterion for preliminary aircraft design

Airlines explain the purchase of oversized aircraft by flexibility within flight operations despite potentially higher fuel consumption and operating costs. In this paper assessment and attributes of flexibility as a criterion is presented and evaluated. A survey was sent to airlines worldwide to explore the motivation for flexibility and desired aircraft characteristics, fleet structure, and flexibility parameters. The results show that flexibility is considered a vital feature and almost as important as direct operating costs. It is also shown that an aircraft's range capacity and commonality in particular facilitate many flexible applications. Overall, higher flexibility is accompanied by higher operating costs.