An Object Oriented Analysis Of Air Traffic Control

1.1 BACKGROUND

The Integration and Interaction Laboratory (I-Lab) project is a development program undertaken by the Center for Advanced Aviation System Development of The MITRE Corporation and sponsored by the Federal Aviation Administration (FAA) Operations Research Service, AOR-1. A first step towards development of an Air Traffic Control (ATC) National Simulation Laboratory (NSL), the I-Lab project has been established by the FAA as a means of incrementally developing the operational and architectural concepts and the requirements for the NSL. The software and architecture of the I-Lab testbed will be used as the basis for establishment of the initial baseline system at the NSL.

As part of the development process for the I-Lab architecture, an object-oriented analysis of the ATC domain was carried out, producing a model of the ATC system. In order to demonstrate the practicality of the ATC model, an experiment (i.e., an integration study involving individual National Airspace System [NAS] subsystems, procedures, and airspace) and two pieces of legacy (existing) software were defined in terms of the ATC model. The experiment model identified needed capabilities and the legacy software models identified existing capabilities. Comparisons of the experiment model with the legacy software models revealed software capabilities still not available.

This document describes the method of analysis, the models constructed, and an example of the practical application of the models.

1.2 OBJECTIVES AND SCOPE

The objectives of the analysis included the following:

• To provide a reference model for software definition -The analysis produced a reference model for defining I-Lab software. It was verified that legacy software can be defined in terms of the ATC model. Object-oriented designs of new I-Lab software can be based upon the ATC model. The ATC model also provides a reference model for the definition of non-I-Lab legacy software or new software which must be integrated with I-Lab software.

• To provide a reference model for experiment definition - The object-oriented model of ATC also provides a reference model for defining experiments. It was verified that an experiment can be defined in terms of the ATC model

• To identify I-Lab functionality needed for the initial application - The initial application is defined as a set of experiments. By comparing an experiment model with legacy software models, new functionality (i.e., not provided by legacy software) needed to conduct the experiment can be identified. Existing software which might be used can also be identified for further evaluation.

• To provide a model for the NSL - An object-oriented analysis performed for the I-Lab can serve as a model for the NSL. No existing object-oriented analysis methodology by itself was sufficient for the task; the analysis resulted in a more useful methodology.

An analysis of ATC can also identify potential areas for automation, beyond those documented by the National Airspace System (NAS) Plan or the Federal Aviation Administration Plan for Research, Engineering and Development (the "RE&D Plan"). This outcome was considered a side benefit, rather than a goal, of the task.

The steps that were followed in meeting the analysis objectives - the test of the methodology - are described in more detail in section 2.1.

The broad scope of study was ATC in the Automated En Route Air Traffic Control Phase 2 (AERA 2) timeframe, i.e., the year 1999 and approximately 10 years beyond. The scope was limited by the following:

• The amount of resources (time and staffing) available - For example, the depth of study in any one area was limited.

• A (subjective) consideration of I-Lab objectives - For example, horizontal (across application) details were emphasized over vertical (within application) details, and applications which were unlikely to be the subject of experiments within I-Lab were omitted.

1.3 DOCUMENT ORGANIZATION

Section 2 of this document describes the methodology developed for the object-oriented analysis. The documentation of the ATC domain model is contained in section 3, which concentrates on the ATC classes, objects, structures and views, and in appendix A, which contains specifications for the classes and objects. Section 4 provides models for an experiment and for two pieces of legacy software, and identifies needed capabilities to support the experiment. As in section 3, section 4 concentrates on classes, objects, structures and views, while appendices B, C, and D provide specifications.