procedures indicate that, in the more complex systems in which cognitive behaviors and strong affective elements come into play through the human user/operator, serious deficiencies can become apparent after the system is delivered and is put to work. One means to avoid such deficiencies involves the early fabrication of prototypes and their evaluation by user groups. Prototypes that could be regarded as virtual representations of an operational system can also serve these purposes. When the end user is so engaged in the design process, it becomes bottom-up (e.g., problem-driven or scenario-based design) rather than top-down. Integration of top-down and bottom-up procedures will probably be needed to achieve optimal cost-effectiveness for the national airspace system of the future.

In addition to bridging the barrier that is likely to exist between ordinary users and design engineers, human factors specialists bring to design deliberations knowledge about human capabilities and limitations that has been acquired by rigorous scientific research. The human factors specialist is also expert in identifying and seeing the implications of subjective user attitudes, opinions, and tastes.

The integrated project team for every major subsystem in the advanced automation system should contain at least one full-time human factors specialist who would have the authority and responsibility to ensure that (a) user participation is timely and extensive, (b) human capabilities, limitations, and values are considered as part of every design decision, and (c) gaps in the knowledge base that could compromise the quality of the resultant system are identified and rectified by appropriately rigorous research.

It is important to consider specific interests of the government as system procurer in the allocation of human factors resources. That is, the final design of a major subsystem should not be the exclusive prerogative of a contractor. A way should be found to ensure that human factors/human engineering is not slighted by contractors as an arbitrary cost-saving ploy. Authoritative oversight is essential in this matter.

Systems that enjoy intensive and extensive user participation in their development are generally more likely to be more usable, effective, and acceptable than systems that are thrust on users after development has been completed.

However, user participation can be expensive and time-consuming—and can lead as easily to ambiguity as to clarity with respect to the choice of design options if good care is not exercised. In particular, users' perceptions can change while the development process is still under way, and user demands can expand over time. The resultant "requirements creep" can seriously disrupt the procurement process. There is a variety of strategies for minimizing the costs, delays, and ambiguities that can come from extensive user participation. Such strategies look at simplification of the procedures of rapid prototyping and the limitation of the use of such procedures to stipulated stages in the system development sequence.

FRONT MATTER (R1-R14)

EXECUTIVE SUMMARY (1-14)

1 OVERVIEW (15-31)

2 TASKS IN AIR TRAFFIC CONTROL (32-53)

3 PERFORMANCE ASSESSMENT, SELECTION, AND TRAINING (54-75)

4 AIRWAY FACILITIES (76-88)

5 COGNITIVE TASK ANALYSIS OF AIR TRAFFIC CONTROL (89-111)

6 WORKLOAD AND VIGILANCE (112-134)

7 TEAMWORK AND COMMUNICATIONS (135-151)

8 SYSTEMS MANAGEMENT (152-176)

9 HUMAN FACTORS IN AIRWAYS FACILITIES (177-196)

10 STRATEGIES FOR RESEARCH (197-225)

11 HUMAN FACTORS AND SYSTEM DEVELOPMENT (226-240)

12 AUTOMATION (241-289)

REFERENCES (290-336)

Appendix A Aviation and Related Acronyms (337-342)

Appendix B Contributors to the Report (343-344)

Appendix C Biographical Sketches (345-352)

INDEX (353-368)