Background - The Air Transportation System Challenge

A justification for the need for Air Transportation System improvement

The Air Transportation System (ATS) has been on the verge of insufficient capacity, with delays and cancelled flights reaching all-time highs and passenger frustration reaching alarming levels. As shown in the figure below, between 1995 and 2000, the peak summer delays more than doubled. This increase in delays skyrocketed compared to growth in traffic. With projected traffic growth at about 4.2% per year¹, delays will continue to escalate at even faster rates, along with their attendant negative impact on the economy and the mobility of the populace of the country. As demand for air transportation continues to increase, the capacity of the air traffic control system needed to accommodate the anticipated growth is falling farther and farther behind. It has become apparent, furthermore, that the present system cannot continue to be scaled up to provide the capacity increases anticipated in the next 15-25 years.

Even with the current crisis and economic downturn associated with the events of terrorism during September 2001, as the air transportation operations, passenger enplanements, and cargo carrying demands recover in the near future, the system will continue to move in the direction of insufficient capacity to handle the projected demand loads. The chart below shows historical data of the demand or growth (enplanements) from 1979-2000. The data shows two historical patterns of a crisis followed by a rebound. The first example is during the 1979 hostage crisis, along with the recession period from 1979-1983. The second example shows the recession period from 1989-1991, including the Gulf War crisis. From these observations, the demand on the air transportation system will be lessened for some period, and then the nation will require the enhancements necessary to promote growth of a stable National Airspace System into the foreseeable future.

The Federal Aviation Administration (FAA) has made significant strides in implementing new technologies, many developed by NASA under the Airspace Systems Program, to try to overcome this problem, notably the Free Flight Phase One technologies. These technologies are the first wave of decision support tools (DSTs) to help the system operators and users improve the performance of the current system. At NASA sponsored workshops on the future of air traffic management, the consensus of the attendees is that the Nation must continue this thrust of implementing enhancements to obtain maximum performance out of the current system.²

Decision support tool development by FAA and NASA will help in meeting demand in the near-term. However, in the long-term, the current system incremental improvement approach³ cannot meet the projected operational demands on the system. The approach is too restrictive: with fixed sectors, aircraft spacing limitations, surveillance gaps, security constraints, and communications bottlenecks, the available degree to which system improvements can help is architecturally limited. A revolutionary change in the fundamental approach to airspace operations and related ATS technologies is needed. The time to explore those concepts and define the needed technologies is now.

AvSTAR Vision and the VAMS Project

NASA proposes that a revolutionary modification in airspace operations is the only real long-term solution to address these obstacles. Accordingly, NASA has proposed and developed an Air Transportation Vision.⁴ This vision, depicted in the image below, is one of providing seamless operations to all vehicle classes across all airspace to provide large increases in movement of people/cargo through:

• Integrated airspace operations
• Sharing of information from distributed sources
• Advanced automation or process mechanization
• Ability to interoperate with new classes of aerial vehicles with unmanned aerial vehicles (UAVs), Small Aircraft Technology System (SATS) vehicles, and reusable launch vehicles (RLVs)
• Human interactive system monitoring and goal setting capabilities

During 2000 and the beginning of 2001, a comprehensive research and development effort (Aviation System Technology Advanced Research (AvSTAR)) was planned in cooperation with the FAA to fulfill this vision. The planning was done under the NASA/FAA Memorandum of Understandin (MOU) on "Airspace System User Operational Flexibility and Productivity," signed by the Administrators of both agencies in 1995 and reaffirmed in October of 1998. In March 2001, during the fiscal year 2002 budget process, specific guidance was received from the Office of Management and Budget (OMB) to:

"Initiate a new effort, Virtual Airspace Modeling and Simulation (VAMS)... to model the airspace environment. In order to meet the demands for the airspace system of the future, a revolutionary change in the fundamental approach to airspace operation will be required. This modeling effort will provide the technical basis to guide policy by exploring revolutionary concepts and technologies, identifying those offering the greatest potential benefit, as well as their limits..."

Thus, the VAMS effort has evolved as an OMB "pass back" and is viewed by NASA, FAA, and the OMB as a precursor effort to the research and development effort. The figure below shows the top-level relationship of the AvSTAR vision and VAMS effort. The articulation of this relationship is that VAMS will develop the concepts, modeling and simulation environments, and necessary technologies to explore the future air traffic management system. The core component technologies element of AvSTAR includes those NASA required technologies that support the FAA's Operational Evolution Plan and technological foundations for NASA's ATM vision as a 'seamless' air transportation system. This technological requirement has been deferred to future years based on budgetary constraints.

To assure that the VAMS Project addresses the interests and concerns of all potential users, NASA/FAA/Industry Workshops were held as part of the planning process. These workshops were held in September of 2000 and March of 2001. Opinions were solicited from the workshop participants and positive comments were received and used in the planning and preparation for the VAMS project. Many of the activities in the VAMS Project are in direct response to the recommendations from the participants of these workshops.

¹ FAA APO-100, FAA Fact Book, October 2001.
² AvSTAR Workshops held in September 2000 and March 2001.
³ The FAA Operational Evolution Plan (OEP) can be found at http://www.faa.gov/programs/oep/
⁴ This vision was first presented by Dr. Robert Rosen of Ames Research Center at the International ATCA 2000 meeting.

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