A Model for Determining Spectral Capacity in the FAA's Air/Ground Communications System

A critical problem that the Federal Aviation Administration (FAA) is currently facing and which will worsen over time is the availability of spectrum to meet future air traffic needs such as adding new runways, adding new sectors, and splitting congested sectors. Growth in very high frequency (VHF) air/ground (A/G) communication due to increased levels of air traffic has led to higher demands in A/G channel requirements for the last two decades. The FAA is currently considering upgrading its A/G communications system to a new technology that promises to provide spectral relief. Concurrently with planning an A/G communications system upgrade, the FAA is also considering new concepts in airspace design (referred to as airspace re-design) to meet its operational needs. Intuitively, based on the new airspace design concepts, and on the design of the new A/G communications system, one could surmise that spectral relief could result as a by-product of either or both of these efforts. Although the main goal of airspace re-design is not to provide spectral relief, but to satisfy operational needs, at least it is hoped that airspace re-design will not worsen the spectrum problem. Because of the magnitude of the undertaking of these efforts, substantial quantitative validation of the impacts of these efforts on the spectrum problem is required before the FAA moves ahead with its plans. To assist the FAA with its decision making regarding these efforts, MITRE/CAASD developed a modeling technique called depletion analysis. The application of depletion analysis is described in this paper to a limited portion of the National Airspace System—the high-en route airspace in the Southeast.