Commercial Low-Altitude UAS Operations in Population Centers

Abstract

Unmanned air systems (UAS) have numerous military, law enforcement, and commercial applications. Commercial potential in particular will not be realized until a comprehensive strategy is developed for safely and fully integrating UAS into the national airs pace system over both rural and urban regions. This paper overviews a broad spectrum of UAS commercial applications to motivate airspace integration. Focus is then placed on use of small to micro-scale UAS in potentially lucrative bu t ultimately challenging benchmark applications: on-demand surveillance over a densely-populated urban region. Following the introduction of urban use cases, we present alternative criteria for small UAS safety that focus not on vehicle preservation but instead on avoiding collateral damage to people and property on the ground as well as to higher-cost airborne assets. We conclude the paper with a discussion of safety preservation when a micro air vehicle over an urban area encounters turbulence or wind shear, a likely day-to-day scenario that can introduce significant risk of a forced landing given realistic constraints on disturbance rejection. This study, led by Raytheon, is part of a NASA Research Announcement activity for Integrating Advanced Concepts and Vehicles into NextGen. I. Introduction he pressing need to maximize commercial transport safety and capacity while minimizing environmental impact has resulted in a next-generation airspace system plan that focuses on two of three parts of the national airspace system: enroute airspace greater than FL100 and the airportal environment near runways. Large unmanned aerial systems (UAS) such as Global Hawk can fit within this structure as on-demand but infrequent operations. However, small UAS (SUAS) operations, where "small" is defined as a UAS under 35 pounds, will occupy airspace well under FL100 and would initially occupy uncontrolled airspace with no to extremely rare entry into congested airportal corridors. As part of the NASA Research Announcement (NRA) activities for Integrating Advanced Concepts and Vehicles in to NextGen, Raytheon and its collaborators, including the University of Michigan, studied the impact of four future vehicle classes on NextGen in 2025 through 2040, including SUAS. This paper investigates the use cases and safety issues arising from SUAS operating in densely- populated urban regions. Currently small UAS operations are conducted with an FAA Certificate of Authorization (CoA) typically granted to entities seeking operations below altitudes GA craft wo uld occupy. While appropriate for initial low-altitude UAS platform flight tests, the CoA does not provide the flexibility to operate commercially over evolving sites of public or individual interest. A limited number of operators, primarily in remote regions, have been granted permission to conduct UAS operations in designated test ra nges. These remote ranges will provide valuable means to test operational protocols, but they will not support a class of on-demand UAS operationseven approaching the freedom current GA and small commercial aircraft operators enjoy today. The primary cited impediment to UAS pervasively operating in the national airspace system (NAS) is increased risk, both real and perceived. Although early UAS maturation has occurred primarily in the DoD sector, if UAS-specific risk could be appropriately computed and controlled, regulatory, air traffic, and operational protocols can be introduced to flexibly accommodate rather than segregate UAS operations. As occupants of primarily uncontrolled airspace, SUAS would share the skies with general aviation (GA) operations. So long as commercial and private UAS and GA activities remain sparse, it may be sufficient to define special-use areas for UAS, or to adopt a simple deconfliction approach such as defining a specific flight altitude for UAS that only must be verified clear when GA traffic tran sits during climb or descent. Emerging "sense-and-avoid" technologies will enable UAS to evade a nearby aircraft, and will ideally be sufficiently small and low-cost to be affixed in most UAS platforms. Given sufficient risk mitigation for UAS operations, we can begin to consider an alternative model, where business use cases predict rapid UAS proliferation in the private and commercial sectors to an equal or even greater extent than ha s been observed in military operations. In this scenario, either the FAA will