Urban Air Mobility: A Primer and Taxonomy
Written by Susan Shaheen and Adam Cohen
Innovative and emerging technologies present exciting opportunities to transform mobility and goods delivery. As long as there have been cars and airplanes, manufacturers and urban futurists have envisioned a future with flying automobiles. As early as the mid-1920s, Henry Ford began imagining a future of “plane-cars” and developed light-weight, single-seat aircraft prototypes. Over the years, numerous companies, such as Chrysler and Curtiss-Wright, built and delivered a variety of concepts intended to test the concept of short-range aerial transportation.
In recent years, technological advancements are enabling numerous companies to build and deliver a variety of prototypes and market-ready products for urban air mobility (UAM). The National Aeronautics and Space Administration (NASA) defines UAM as a safe and efficient system for air passenger and cargo transportation within an urban area, inclusive of small package delivery and other urban unmanned aerial systems (UAS) services, which supports a mix of onboard piloted, ground-piloted, and increasingly autonomous operations.
The concept of urban air mobility is not new. Between the 1950s and 1970s, a number of helicopter services provided short-range passenger flights in Los Angeles, New York, and San Francisco. New York City was the largest market offering more than 30 daily flights between JFK airport, Newark, Wall Street, and the Port Authority, serving approximately 500,000 passengers annually at its peak. One-way fares averaged between US$4 and $11 (approximately US$32 to $88 adjusted for inflation). At its peak, PanAm offered hourly helicopter connections between Midtown and JFK’s WorldPort, allowing passengers to check-in at the PanAmerican building in Midtown just 40 minutes prior to their flight departure at JFK. The service was discontinued in 1977 when metal fatigue caused a rooftop crash killing five people. In the 1980s, Trump Air launched a scheduled helicopter service between Wall Street and LaGuardia airport, connecting to Trump Shuttle flights.
By the 2010s, on-demand aviation services similar to transportation network companies (TNCs) were envisioned. In 2014, BLADE began offering an on-demand helicopter service using a smartphone app, arranging flights between passengers and charter operators. This was followed by SkyRyde in 2018, offering on-demand flights linking passengers to charter fixed-wing operators in Southern California. Starting in July 2019, Uber Copter is expanding its helicopter service in New York City .
In recent years, a variety of technological innovations are converging that are reshaping aviation and enabling new aircraft, services, and business models. Automated and electric vehicles have the potential to change landside access and airside operations. Electric, vertical take-off and landing (eVTOL) and unmanned aircraft systems (UAS) present opportunities and challenges for skyport infrastructure, airport access, and air traffic management. The need to pursue carbon neutral propulsion strategies through electrification, sustainable fuels, or other technologies also represent notable challenges that will continue to confront the industry.
A closer look at UAM reveals marked differences in propulsion (e.g., gasoline and electric); design; technology; range; and compatibility with existing infrastructure. UAM is being discussed in a number of contexts including: disaster relief, goods movement, and passenger transport. Not surprisingly, UAM technologies can be controversial in light of safety concerns, noise and privacy considerations, land use/infrastructure impacts, and consumer costs.
Today, a number of firms are developing a variety of piloted, remote piloted, and automated aerial vehicles and aircraft. For example, in the passenger UAM marketplace, some original equipment manufacturers (or OEMs) have developed electric fixed-wing and quadcopter offerings often with more limited range, while others have produced longer-distance, gas-powered prototypes. Some employ VTOL capability (e.g., Airbus , Bell , Joby Aviation , KittyHawk , eHang , Lilium , etc.), while others may require a landing strip (e.g., short takeoff and landing aircraft, known as STOL). Some are intended for aerial flight-only, while others are designed with dual capability to fly and drive on existing streets (e.g., AeroMobil , sometimes referred to aerial vehicles and roadable aircraft). Similarly, a variety of technologies are being explored by retailers and logistics companies to reimagine urban goods movement. Some of these include unmanned aerial vehicles (UAVs) (commonly referred to as drones among the public); parachute delivery (e.g., Amazon); aerial warehousing and distribution (Amazon and Walmart ); and a hybrid truck/drone delivery system (UPS). UAVs are a component of unmanned aircraft systems (UAS) that include the aircraft and associated elements related to safe operations, which can include control stations, data links, support equipment, payloads, flight termination systems, and launch/recovery equipment (41 CFR 102–33.20).
At present, the industry lacks a taxonomy and standardized definitions for this emerging ecosystem of urban aviation. In some cases, this can create challenges in regulation and certification and contribute to confusion and misperceptions by the public about safety, aircraft capabilities, and service characteristics. A taxonomy with standardized terms and definitions is needed to help clarify differing terms (both among the public and private sectors, domestically, and internationally).
While the development of a taxonomy and definitions necessitates public and private sector stakeholder collaboration, there are key defining characteristics to consider. The UAM ecosystem can be organized in a number of ways including:
· Design characteristics, such as passenger capacity, propulsion, airframe, or aircraft types (e.g., wingless designs, electric rotorcraft, aircraft that use any of its thrusters for vertical lift and cruise vs. aircraft that use independent thrusters for vertical lift and cruise);
· Operational characteristics, such as VTOL and aircraft that can fly and also be driven on roads (sometimes referred to as roadable aircraft);
· Training and knowledge requirements for pilots and operators;
· Airworthiness certification approaches, based in part or whole on established Federal Aviation Administration and international processes;
· Service type or use case (e.g., scheduled service, charter service, unscheduled service, passenger mobility, goods delivery, etc.); and
· Distinctions based on piloted, remotely piloted/operated, and autonomous aircraft (note the term autonomous is used rather loosely to describe fully autonomous flight, as varying levels of autonomy can be used to describe specific aircraft systems and phases of flight).
One way of viewing this ecosystem is as a taxonomy that blends these key characteristics. The figure below shows three broad categories of use cases:
1) Passenger mobility (comprised of aircraft and rotorcraft);
2) Urban goods delivery (comprised of a broad ecosystem of manned and unmanned delivery systems); and
3) Hybrid systems (a broad category intended to capture systems that blur traditional categories, such as roadable aircraft and trucking/drone systems, e.g., the UPS concept that pairs drones to ground-based delivery trucks).
Within each of these broad categories, distinctions can be made depending on whether there is a:
1) Pilot on-board (including fully piloted and partially automated flight, i.e., partially automating a particular phase of flight, such as take-off and landing);
2) The vehicle is remotely piloted or operated (e.g., operations centers with remote operators controlling multiple aircraft); or
3) The aircraft and/or unmanned aerial vehicles (often called drones) are fully automated (or pilotless).
A Taxonomy for Emerging Urban Air Mobility Ecosystem
For many years, helicopter services have been available in numerous markets. However, new advancements in technology are enabling a variety of aircraft concepts, such as VTOL, electrification, roadable designs, and goods delivery applications, such as drones and aerial warehousing concepts. Given the ongoing evolution in UAM, a taxonomy can help to provide more consistent terminology and guide public policy. While there are many ways to organize this taxonomy, public and private sector stakeholder collaboration is needed to further develop industry terms, concepts, and policy.
Susan Shaheen and Adam Cohen are co-authors of the recently released NASA market study on Urban Air Mobility.
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Please note that this article expresses the opinions of the authors and does not reflect the views of NASA or Move Forward.
