  In this article, we present the development of a two-step optimization
framework to deal with the design and selection of aircraft departure routes
and the allocation of flights among these routes. The aim of the framework is
to minimize cumulative noise annoyance and fuel burn. In the first step of the
framework, multi-objective trajectory optimization is used to compute and store
a set of routes that will serve as inputs in the second step. In the second
step, the selection of routes from the set of pre-computed optimal routes and
the optimal allocation of flights among these routes are conducted
simultaneously. To validate the proposed framework, we also conduct an analysis
involving an integrated (one-step) approach, in which both trajectory
optimization and route allocation are formulated as a single optimization
problem. A comparison of both approaches is then performed, and their
advantages and disadvantages are identified. The performance and capabilities
of the present framework are demonstrated using a case study at Amsterdam
Airport Schiphol in The Netherlands. The numerical results show that the
proposed framework can generate solutions which can achieve a reduction in the
number of people annoyed of up to 31% and a reduction in fuel consumption of
7.3% relative to the reference case solution.
