AwSim Architectural Highlights

AwSim is a general-purpose trajectory simulator aimed at providing a realistic air traffic data source for ATC/ATM systems that can be used in the areas of testing, modeling and training.

Trajectory Simulation

The main output produced by AwSim is a stream of trajectories (i.e. objects encapsulating a 4-dimensional profile of a moving vehicle in an Earth center coordinate system). The segments from which trajectories are built can be made to snap to an airspace structure (i.e. aerodromes, fixes and airways) or alternatively, they can be generated in a free-flight unrestricted fashion. The user can set the parameters that control the statistical distribution functions from which the population of segments is drawn. The variables under control (all of which have their separate distribution function) are: segment speed, segment length, Gaussian transverse deviation, segment altitude, start and end location of the trajectory, number of segments in a trajectory, and start time.

When generating trajectories, AwSim randomly chooses the departure and arrival aerodromes based on a prepared aerodrome table that includes the airport capacity and optionally a 'hub' designator (which allows it to be connected to any other 'hub' airport). For a non-hub airport, AwSim accepts for each airport the list of its connecting airports along with relative traffic weight. Thus, for instance one can configure a non-hub airport A, connecting (i.e. accepting flights between) three other airports B (30%), C (25%), and D (45%) with the fraction of the traffic split as indicated by the percent figures.

A time weighing function allows the controlling of the traffic load depending on the time of day. This time function together with the traffic coefficients for each airport allows for a very flexible and realistic control of the generated traffic patterns.

The AwSim output port writes trajectories by default, but it also has the option of writing text messages (i.e. ICAO flight plans) suitable for sending via AFTN or message gateway of any ATC system. In this manner AwSim can be used as a source of input for any ATC/ATM system.

Conflict Prediction

The AwSim Conflict Prediction (CPR) process examines the AwSim trajectories (or trajectories from other sources) and determines if any violations of the separation rules exists. CPR provides the relevant conflict data to AwSim metrics application for display and comparison purposes. CPR applies the U.S. domestic separation rules of 5nm lateral separation, 10 or 20 FL vertical, depending on altitude, or other adaptable parameters. CPR provides an option to use block altitudes, or to interpolate altitudes during climb/descent.