TMAC
(Last update: 3/25/96 JKK)
1. Primary Model Category
Simulation tools to analyze flow management strategies and system level evaluation of alternative operational concepts. Tools were developed to support FAA concept exploration and development.
2. Summary
TMAC is a set of capabilities and thus more than a single model. It uses aircraft flight plans, dynamics, and traffic management strategy (e.g., free-flight, limited airborne holding) to determine conflicts and delays. Uncertainties in aircraft trajectory projections are also modeled to provide realistic inputs to traffic management logic. The user is able to interact with the models for concept development. TMAC is complex, intended to solve specific problems and not meant to be a generic modeling tool. It is not available outside MITRE.Competing models include SIMMOD, RAMS, NASPAC, TAAM, and FLOWSIM.
3. Input Requirements
Aircraft routes, flight plans, aircraft dynamics, ground delays, traffic management logic (e.g., free-flight, structured ATC, or airborne holding), airport capacity.
4. Outputs
Travel times, delays, conflicts.
5. Major Assumptions
Assumes given airport capacities but no en route sector capacities. No conflict resolution algorithms are included.
6. Computational Characteristics
Platform: 2 - HP 755 workstations (one for Sybase, one for the model)Operating System: HP-UX 9.0.3
Memory: 384 MBytes RAM, 2 GByte Hard Drive
Software Requirements: Sybase 4.9.2, Vads (Verdix/Rational) 6.2, (Perl, C, ADA).
Documentation: No formal documents but adequate user's guides reportedly exist.
Startup Effort: High
User Interface: Adequate (GUI)
Typical Run Time: best case is 0.9 real time (i.e., slower than real time)
7. Modularity and Flexibility
TMAC is a compilation of several modules and building blocks but its complexity and focus on specific problems makes it difficult to generalize to other problems. The model is somewhat flexible in that it has been used to examine diverse traffic management strategies but is not available to users outside MITRE.
8. Status
Under continual improvement and use at MITRE. The focus has been on solving specific problems rather than the development of a more generic modeling tool.
9. Extent of Model Verification
Average 2-minute savings under free-flight determined by TMAC has been corroborated by a simulation using NASPAC and (independently) by a Delta Airlines study.
10. Principal Applications
Evaluation of traffic management strategies: limited airborne holding, free-flight vs. structured control, cooperative slot exchange, arrival flow management, airline schedule volatility, classification of weather day types for TFM.
11. Availability
Not available outside MITRE. Intended as an internal tool only.Contact: John Pyburn, MITRE Corporation, (703)-883-5546, jpyburn@mitre.org
12. Information for Model Evaluation
Presentation and interview with John Pyburn, MITRE, 12/18/95.
13. Summary Evaluation
TMAC is a complex, multi-element simulation and analysis tool intended primarily for use in evaluating traffic management strategies. Although it is intended primarily as a strategic concept analysis tool, its level of detail is higher than that of NASPAC. The user is able to enter flight plans, aircraft type, ground delays, and traffic management strategy. Outputs include travel times, delay metrics, and conflicts. There is no conflict resolution, so the model is unable to show the impact of conflicts on traffic flow. The model is not available outside MITRE. TMAC is being actively used at MITRE in a number of TFM studies and to support the refinement and evaluation of the future NAS concept of operations.
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