MIT AATT Model Project

TOPAZ: Traffic Organization and Perturbation AnalyZer

Note: This review is of an old version and is to be replaced by new review currently being edited.

(Last Update: 5/14/96, KK)

1. Primary Model Category

Collision risk model

2. Summary

TOPAZ (Traffic Organization and Perturbation AnalyZer) is a safety/capacity assesment tool for evaluation of new route structures in combination with new ATM concepts for a multitude of ATM applications. TOPAZ evaluates the collision risk between aircraft within an arbitrary network of lane segments by calculating the expected number of aircraft collisions on the basis of a generalized version of the Reich collision model (Bakker & Blom, 1993). Collisions are determined as events in which simultaneous loss of lateral, vertical, and longitudinal separation occurs between aircraft flying within a network of lane segments in 3D airspace. Thus all types of collisions are accounted for.

TOPAZ simulates the probability density functions along the 3D route structure rather than the individual aircraft trajectories and evaluates the collision risk between aircraft as a function of traffic flow. Maximum capacity is determined as that where the risk coincides with the selected target value.

3. Inputs

TOPAZ requires as inputs all lane segments of the route structure, the expected 3D trajectories of the aircraft in time and the probability densities of the deviations from the above trajectories (in terms of Gaussian-mixture or double-exponential densities).

4. Outputs

The macroscopic simulation calculates the collision risk as a function of traffic volume.

5. Major Assumptions and Limitations

TOPAZ requires detailed routes and expected deviation distributions.

6. Computational Characteristics

TOPAZ has been developed in Pascal and is installed on a 486 PC.

7. Modularity and Flexibility

TOPAZ was to be extended in 1995 with a module for evaluating probability densities of deviations using stochastic dynamic models of aircraft within new ATM concepts.

8. Status

TOPAZ has been operational at the NLR since 1992.

9. Extent of Model Verification

Unknown

10. Principal Applications

Collision risk modelling and assessment for safety and capacity assessment for evaluation of new route structures in combination with new ATM concepts. Some recent projects have been:
  • Evaluation of candidate route structures for SUATM (Single Unified ATM Systems; CEC DGXIII)
  • Evaluation of the Dependent Converging Instrument Approach Procedure (Netherlands Dept. of Civil Aviation (RLD) and Netherlands ATC)

11. Availability

TOPAZ is available at the NLR, Netherlands.

12. Information for Model Evaluation

    Bakker, G. J. & Blom, H., Air Traffic Collision Risk Modelling, Proc. 32nd IEEE Conf. on Decision and Control,Dec. 1993, pp1464-1469 (NLR report TP 93292 U)

    Bakker, G. J. & Blom, H., TOPAZ Features

13. Summary Evaluation

TOPAZ is an analysis tool for the numerical evaluation of collision risk using the generalized Reich collision risk model as described in the paper (Bakker & Blom, 1993).

TOPAZ allows safety and capacity assessment for evaluation of new route structures in combination with new ATM concepts. Collisions of all types are considered: head-flank, head-head, head-tail, flank-flank and top-bottom.

TOPAZ simulates the probability density functions along the 3D route structure rather than the individual aircraft trajectories and evaluates the collision risk between aircraft as a function of traffic flow. Maximum capacity is determined as that where the risk coincides with a preselected target value.

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