Defining Human-Centered System Issues for Verifying and Validating Air
Traffic Control Systems

Kelly Harwood
CTA INCORPORATED, Moffett Field, CA, USA 


Abstract

Over the past 40 years, the application of automation to the U.S. air
traffic control (ATC) system has grown enormously to meet significant
increases in air traffic volume.  The next ten years will witness a
dramatic overhaul of computer hardware and software in enroute and
terminal facilities to accommodate future growth in air traffic
activities.  From a human factors perspective, notable changes are the
new controller workstations or sector-suites which will provide such new
features as adjustable consoles, graphic situation displays, and
electronic flight strips.  This modernization will provide the basis for
introducing automated functions that will transition the controller from
tactical control to strategic traffic management.  The U.S. Federal
Aviation Administration (FAA) recognizes the importance of an effective
human-system interface to successful operations (Kloster and Zellweger,
1987).  Because various phases of test and evaluation are just around
the corner for these new system upgrades, questions arise concerning
what aspects of the human-system component must be addressed to verify
system safety and efficiency.  Such questions are not trivial.  They
strike at the heart of the "omnipresent criterion problem" (Christensen,
1958), that is, the difficulty of defining criterion measures for
verifying and validating complex systems.

This paper first discusses the criterion problem, focusing on
the unique constraints within ATC.  The central argument is that before
criteria and measures can be specified, human-centered issues associated
with ATC technology upgrades must be carefully determined.  An approach
is discussed for disclosing such issues drawing on techniques and
philosophies from traditional human factors engineering, cognitive
systems engineering, and ethnography.  The approach is illustrated for
the Center Terminal Automation System (CTAS), a set of automation tools,
currently under development and evaluation by NASA-Ames in partnership
with the FAA.  CTAS will assist air traffic personnel in managing
arrival traffic flow in the center and terminal environments.