“…We also assume ordered time windows, that is, we assume that the latest possible operation times of all pairs ða; a 0 Þ of aircraft are in the same order as their target times, i.e., T a 6 T a 0 () L a 6 L a 0 . Under these assumptions, all feasible ASP instances have an optimal solution, in which the aircraft of the same aircraft class are scheduled FCFS, i.e., for wðaÞ ¼ wða 0 Þ^T a < T a 0 ; C a 6 C a 0 holds for all ða; a 0 2 A; a -a 0 Þ (Briskorn and Stolletz, 2014;Ghoniem et al, 2014). There are no sequencing restrictions for pairs of operations from different classes.…”