The Flight Routing & Scheduling Model generates aircraft trips according to segmented passenger and freight flows. Based upon the passenger and freight flows coming from the Air Transport Demand Module, this model outputs aircraft trips, in the form of a flight schedule, to the Aircraft Movement Module and to an internal LTO Operations Model. Aircraft classes used are also output to the Aircraft Technology & Cost Module, which returns costs and emissions (the latter to the internal LTO Operations Model). The generation of the schedule includes identification of aircraft sizes, flight frequencies, departure times, and passenger load factors, by flight segment. These factors are modelled as a function of passenger and freight demand, segment length, and in future developments of the model, average delay (from an internal Delay Calculator) and aircraft cost (from the Aircraft Technology & Cost Module) to capture airline response behaviour. These relations are derived from current and historic schedules, demand data, load factors, delays, and aircraft class and size statistics.
Alternatively to the Scaled Routing Model in the Air Transport Demand Module, the Flight Routing & Scheduling Model also simulates the airline response to capacity constraints. By maximizing airline profits, i.e., the aggregate difference between airline revenues and costs for each possible flight segment, a linear optimization routine allocates passengers to various routes in different periods of the day, subject to the available aircraft fleet. This model will reproduce the global routing structure in the base year and endogenously adjusts the routing structure to capacity constraints, eventually resulting in a changing air traffic network over time. The formulation of this model has just begun and first tests based upon a limited set of airports are promising.
The internal LTO Operations Model includes two functions: modelling aircraft ground operations; and modelling landing and take-off operations. The outputs of these models are LTO path, taxi and flight times, and emissions (calculated relative to emissions by class input from the Aircraft Technology & Cost Module), which are direct inputs to the Local Air Quality Module. The modelling of ground operations includes simulating taxi demand and unimpeded taxi times. Taxi demand is defined by the flight schedule input from the Flight Routing & Scheduling Model, and airborne delay input from the Aircraft Movement Module. Unimpeded taxi times are obtained directly from data for airports in some regions (e.g. US, EU), whilst parametric modelling based on other airport characteristics is required for those regions for which it is not available.
*Courtesy: Univ of Cambridge