MIT AATT Model Project

NARSIM

(NLR ATC Research Simulator, NLR: Nationaal Lucht-en Ruimtevaartlaboratorium, National Aerospace Laboratory, Netherlands)

(Last Update 6/18/96, KK)

1. Primary Model Category

Real-time Air Traffic Control simulation with humans and real ATC systems in the loop.

2. Summary

NARSIM is NLR's in-house Air traffic Management (ATM) and Human-Machine Interface (HMI) research simulator facility. It simulates aircraft, radar, weather and automated air traffic control. NARSIM has been used for research and development of advanced automated tools and thedevelopment integration of ground and air based systems. The advanced automated tools aid in prediction of aircraft trajectories, conflicts, and excessive deviations from the planned routes. Research in Human-Machine Interfaces is intended to aid in Air traffic controllers' workload reduction.

NARSIM is also being used in international research projects such as PHARE for 4D ATM concepts which is the research part of the European Air Traffic Control Harmonisation and Integration Program (EATCHIP) conducted by Eurocontrol for the development of next decade's European Air Traffic Management System (EATMS).

3. Inputs

Complete simulation of an air traffic control system would typically require comprehensive data on the environment and agents. NARSIM premodels the basic ATC system so modifications or new concepts can be incrementally added for evaluation. Playback of real live or recorded traffic can be used for realism. Additionally computer generated traffic with pseudopilot (human blipdrivers on computer consoles) assistance may be utilized.

4. Outputs

Generally NARSIM operates in near-real time and recordings of the entire modeled and real state can be made for post analysis of events and agent or system performance.

5. Major Assumptions and Limitations

The basic ATM system modeled is that of the Netherlands and neighboring EU countries (to a limited scale). It is possible to adapt the system to other environments. The system operates in real time and principally provides a substitute for experimentation in real ATC systems. The realism of the simulation is intimately tied up with the ability to generate realistic conditions and for that purpose real live or recorded data and pseudopilots (human blipdrivers) flying computer generated traffic are used by NARSIM.

A fast time mode without humans in the loop is also available for evaluation of conflict alerting and detection tools as an example. This mode can be upto 50 times faster than real-time depending on the complexity of the simulation and computer performance.

6. Computational Characteristics

NARSIM runs principally on an HP 9000 model 887, running HP-UX with approximately 110 MIPS (45MFLOPS), 128MB memory and about 4GB disk space for simulations with moderately heavy algorithmic load. For blipdrivers and software development purposes 9 X-terminals are connected to the main NARSIM computer.

The display computers are HP 9000 models 300 and 700. The display controllers for the ATC Controller positions are two Metheus Omega 3720 controllers (being replaced by new Metheus and Barco controllers, compatible with X-Windows) connected to two 20"x20" Sony raster monitors. The main NARSIM computer links all NARSIM computers to the Internet through the NLR wide network.

7. Modularity and Flexibility

NARSIM has a modular structure, implemented using a custom CORBA-like Client/Server middleware. Modules in different languages (typically C, Ada and Fortran) can possibly run on different hosts without any knowledge of underlying distributed system. The middleware makes it possible to add and remove modules during a simulation, and also allows for connecting NARSIM to other ATC simulators or flight simulators. Several international distributed simulations have been held, connecting NARSIM to a NASA flight simulator, the NLR flight simulator and ATC simulators from Eurocontrol (France) and DLR (Germany).

8. Status

NARSIM is a relatively mature simulation system and has been used in a variety of ATM studies.

9. Extent of Model Verification

NARSIM has been used extensively and as a large proportion of the simulation is essentially real, model verification is perhaps not an issue.

10. Principal Applications

Evaluation of new ATM concepts and procedures in realistic partially simulated ATC environment.

11. Availability

NARSIM is available at the NLR, Netherlands.

12. Information for Model Evaluation

Michiels, R., et. al, NARSIM Homepage, NLR, July 21st, 1994, http://www.nlr.nl/public/fac/narsim/index.html

NLR NARSIM Brochure

13. Summary Evaluation

NARSIM is NLR's ATM research simulator and supports ATM research within NLR. This includes evaluating new operational procedures, building, testing and evaluating new controller assistance tools and prototyping man-machine interfaces. NARSIM includes the following tools:

  1. The Trajectory Predictor(TP) tool which, based on an aircraft's flightplan, flight progress, current position and meteorological data, computes and stores the expected 4D-trajectory.

  2. The ACOD (Area Conflict Detection) tool which supports the air traffic controller by detecting conflicts between aircraft using both planning data and actual radar data,and can therefore be considered as a medium term planning conflict detection tool.

  3. The STCA (Short Term Conflict Alert) tool supports the executive air traffic controller by detecting future separation infringements between aircraft from data supplied by the radar data processing system, and can therefore be considered as a safety net tool for short term periods.

  4. The FPM (Flight Position Monitor) supports the air traffic controller by monitoring flight progress, detecting deviations from the planned route and possibly suggesting corrective actions.

NARSIM is linked to the Netherlands ATC system (Schiphol) providing live radar data in ASTERIX format over a 9600 baud line. To evaluate new FMS concepts, this link is used to transmit information such as tracked radar data.

For evaluation of controller assistance tools on NARSIM there is a facility to play back recorded traffic. These recordings include radar, flightplan and meteo data as available in the current SARP system. NARSIM can also play back traffic recordings from the Maastricht Eurocontrol centre. The collection of recorded live-traffic (approximately 30 hours) includes average and most special circumstances to appear in every-day air traffic control. Special recordings include high traffic loads due to diverted traffic from surrounding airports and bad weather conditions. To create extreme conditions several recordings can be mixed to increase the amount of traffic.

The simulation scenarios for the air system are based on a set of initial flight-plans. The scenario generator has parameters to select certain types of flight and the number of flights per minute (continuous or with randomized intervals) for each type. The output of the scenario generator is editable, and final manual adjustments are made to get things `just right'.

NARSIM presently simulates almost all important entities involved in current air traffic control including the air traffic system, parametrized radar models, several ATM tools and display software. From a practical point of view this means that NARSIM can simulate most aspects of a real contemporary air traffic control system with some human help (such as the blipdrivers).

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