Profit-based network level evaluation of aircraft block times

For the replacement of todaýs aircraft, a significant reduction of mission fuel burn and noise is targeted by various future studies to achieve promoted emission targets. A Cruise Speed Reduction (CSR) should result in significant fuel burn savings, however, also leads to network-wide implications. The framework presented in this paper goes beyond an usual aircraft fuel burn trade-off study. For a holistic evaluation of the economic impact of changed block times, different models for aircraft performance, aircraft scheduling, Direct Operating Cost (DOC) and passenger demand need to be applied. Therefore, aircraft designed for cruise speed Mach numbers (M) of M0.66-0.82 based on ducted fan and open rotor propulsion technologies were analysed regarding their impact on block times. Based on an operational evaluation of schedule disruptions, speeds down to M0.70 seem feasible. Echoing this result, DOC analyses demonstrated the lower bound of CSR should be set to around M0.70. In contrast, taking airline yields into account, the results show that for aircraft using open rotor or turbofan propulsion technology an optimized design cruise speed is around M0.78-0.80.