Content uploaded by Bojan Lukic
Author content
All content in this area was uploaded by Bojan Lukic on Mar 22, 2024
Content may be subject to copyright.
TECHNOLOGY REQUIREMENTS FOR THE DEVELOPMENT OF AIRCRAFT
FOR URBAN AIR MOBILITY – STATUS QUO
Bojan Luki´c, German Aerospace Center (DLR), Braunschweig, Germany
Umut Durak, German Aerospace Center (DLR), Braunschweig, Germany
Abstract
Urban Air Mobility (UAM) refers to the transportation of people and goods using vertical takeoff and landing (VTOL)
aircraft in urban areas. It is seen as a potential solution for the increasing traffic congestion and transportation challenges
in cities. The concept of UAM involves a network of skyports, where passengers can transit between ground-based
transport, such as cars and trains, to VTOL aircraft. This has the potential to provide faster and more efficient
transportation, while reducing greenhouse gas emissions and noise pollution. Despite its potential benefits, UAM faces
various regulatory and technical challenges before it can be widely adopted and integrated into existing transportation
systems. Due to the operating conditions for urban aircraft being fundamentally different from the existing mature ones
such as passenger airplanes, important aspects for their development need to be considered. The research from this
paper explores the major high- and low-level technology requirements for achieving airworthiness of urban aircraft. From
the selection, five main requirements for successful aircraft operation in urban airspace have been condensed. These are
safety, scalability, performance, cybersecurity, and interoperability. The research shows that the success of UAM relies
on the development of innovative technologies to design and manufacture aerial vehicles that are safe, efficient, and
sustainable. Regulators must also establish a clear legal framework for the certification of aerial vehicles and operators,
ensuring safety, security, and interoperability.
1. INTRODUCTION
Urban Air Mobility (UAM) is a fast-evolving concept that
has gained significant attention in recent years. The idea
behind UAM is to enable air transport within urban areas,
allowing people and goods to travel quickly and efficiently
while reducing congestion on the ground.
The concept of UAM has its roots in the early days of avi-
ation. In the late 19th century, early pioneers of aviation,
such as the Wright Brothers, experimented with different
forms of aircraft that could fly short distances. The first
commercial air service started in 1914 when a biplane flew a
route between St. Petersburg, Florida, and Tampa, Florida.
Copyright Statement
The authors confirm that they, and/or their company or
organization, hold copyright on all of the original material
included in this paper. The authors also confirm that they
have obtained permission, from the copyright holder of any
third-party material included in this paper, to publish it as
part of their paper. The authors confirm that they give
permission, or have obtained permission from the copy-right
holder of this paper, for the publication and distribution of
this paper as part of the ERF proceedings or as individual
offprints from the proceedings and for inclusion in a freely
accessible web-based repository.
It was around that time when the idea of flying cars (Ref. 1)
surfaced. Examples of such flying cars are the Ford Flivver
from the 1920s, the Aerobile from 1937, or the Airphibian
from the 1940s. Many of the early efforts to develop hy-
brid planes failed because of fatalities (Ref. 2) and lack of
funding (Ref. 3,4). Initially funded by the Canadian Gov-
ernment, the Avrocar is considered the first early vertical
takeoff and landing (VTOL) aircraft designed for military
use. However, it was abandoned due to high costs. In
1958, the U.S. Army and Air Force took over the project,
but the flying-saucer-shaped aircraft faced thrust and sta-
bility problems. As a result, the project was terminated
in 1961 (Ref. 5). None of these early concepts of urban
aircraft achieved commercial success.
From the 1950s until the 1980s, a number of operators be-
gan offering UAM services using helicopters in various cities
including Los Angeles, New York City, and the San Fran-
cisco Bay Area. For example, New York Airways began pro-
viding passenger service between Manhattan and LaGuardia
in the mid-1950s. These early passenger helicopter services
were made possible through a combination of helicopter
subsidies, which were terminated in 1966, and airmail rev-
enue in the United States (Ref. 6). Over the next few
decades, aircraft designs advanced as technology improved,
leading to the development of more mature VTOL aircraft
and other novel forms of flying vehicles.
49th European Rotorcraft Forum 2023
DocumentID: 590061
1
CC BY-SA 4.0
doi: 10.25967/590061
The concept of UAM, as we know it today, emerged in the
early 2000s with the adoption of drone concepts into novel
aircraft for cargo and passengers (Ref. 7). As the technol-
ogy improved, drones began to be used for a wide range of
applications, including aerial photography, agriculture, and
search and rescue. Around the same time, increased ur-
banization and population growth led to rising traffic con-
gestion in cities worldwide, leading researchers and trans-
port providers to consider using drones and other aircraft
to provide transport services within urban areas. In 2017,
the US Federal Aviation Administration (FAA) established
the Unmanned Aircraft System Integration Pilot Program
(IPP), which sought to explore the feasibility of integrating
drones and other UAM vehicles into existing transport in-
frastructure (Ref. 8). This program was followed by numer-
ous governmental initiatives around the world, e.g. Ref. 9,
10, aimed at utilizing the potential of UAM in providing
efficient and sustainable public transport in urban areas.
Since then, many companies, including Uber, Boeing, and
Airbus, have entered the UAM market, investing heavily in
the development of VTOL vehicles (Ref. 11,12). These ve-
hicles use advanced electric propulsion systems, which offer
several advantages over traditional aircraft, such as reduced
noise pollution and fewer emissions. As the technology con-
tinues to advance, UAM could soon provide a fast, efficient
and sustainable transport solution for people and goods in
urban areas.
Today, UAM is defined ”as an air transportation system
for passengers and cargo in and around urban environments
[...], offering the potential for greener and faster mobility
solutions” (Ref. 13). Several whitepapers by Volocopter
(Ref. 14), TTI TE Connectivity (Ref. 15), the National
Aeronautics and Space Administration (NASA) (Ref. 16)
and others (Ref. 17–19) have been published over the last
few years, illustrating the topicality of UAM in this day and
age. However, there are certain requirements which need to
be met in order for UAM to be a certifiable and acceptable
means of transport for the public.
The remaining work is structured as follows: In chapter
2, the status quo and research developments for UAM are
discussed. In the main part, chapter 3, five major tech-
nology requirements for the development of UAM are pre-
sented. The requirements and their implication in UAM
are discussed in chapter 4, before the paper is concluded in
chapter 5.
2. RELATED WORK
Related work regarding the requirements for next-generation
avionics in UAM is sparse. As the technology is just now
starting to thrive, mostly high-level requirements and con-
straints, such as social acceptance and infrastructure regu-
lations are discussed in current publications.
Two important publications discussing the status quo and
current research in UAM are from Straubinger (Ref. 20)
and Pons-Prats (Ref. 21). In her paper, Straubinger pro-
vides a comprehensive overview of various aspects related
to UAM. The paper covers topics such as concepts of op-
eration, market actors, integration into existing transporta-
tion systems, and UAM transport modeling and simulation.
Overall, Straubinger provides valuable insights into the cur-
rent state of UAM research and highlights the challenges
and considerations involved in its implementation. Pons-
Prats shows the need for new mobility concepts and UAM
as disruptive technology filling this need. The authors dis-
cuss the importance of technological advancements, par-
ticularly in batteries and electric and distributed propulsion
systems. Technological advancements facilitate the design
of novel aircraft types with VTOL capabilities. The paper
mentions challenges to the deployment of UAM. However,
these challenges are not further specified.
The authors of the paper Ref. 22 present an analysis of the
operational constraints that may affect the implementation
and scale-up of UAM services in Los Angeles, Boston, and
Dallas. The objective of the study is to identify potential
challenges and limitations that could impact the growth
and viability of UAM systems. Five major overarching con-
straints were identified. The constraints indicate that pro-
posed UAM operations may face similar hindrances as the
previous helicopter air carrier operations despite advance-
ments in technology and business models. Examples for
such hindrances are safety issues and rejection of access to
saturated airspace.
The paper Ref. 23 by Reiche explores the advancements
and potential applications of UAM systems for passenger
and air cargo transportation within urban areas. It dis-
cusses the challenges and potential barriers related to ad-
verse weather conditions and provides a weather analysis
methodology used to develop a climatology for UAM oper-
ations. It highlights the need for further research and anal-
ysis to identify potential weather barriers and their effects
on safety, cost, and efficiency in UAM operations.
In Ref. 24, Stelkens-Kobsch and Predescu from the German
Aerospace Center (DLR) emphasize the need to address
security concerns in the development and implementation
of UAM systems. The paper highlights the harmonization
of different states’ legacy approaches to enable a seamless
flow of traffic and the inclusion of various types of vehicles
in controlled airspace. The main focus with the security
task of the project is on identifying primary and supporting
assets, listing threats, and identifying vulnerabilities that
could be exploited in urban airspace.
Athavale et al. discuss the chip-level considerations re-
quired to enable dependability for VTOL and UAM systems
in their paper (Ref. 25). It covers the critical drivers in
future mass-produced VTOLs, the integration of modern
49th European Rotorcraft Forum 2023
2
CC BY-SA 4.0
commercial off-the-shelf computing and communications
technology, and the impact on air traffic control systems
and UAM avionics. The conclusion of the work states that
advancements in Artificial Intelligence (AI) and communi-
cations technologies, along with functional safety strategies,
are making it possible to enable capabilities for VTOL and
Urban Aircraft Systems (UAS). The core of any VTOL oper-
ation is an efficient, safe, secure, scalable, and cost-effective
air traffic control system.
Much of the presented literature either covers high-level
requirements or specific technologies required for UAM op-
erations. Some examples are high-level security concerns,
operational constraints, and integration into existing trans-
portation. The paper at hand makes a contribution to the
research field of UAM by compiling a broad but precise
spectrum of technology requirements for supporting aircraft
operation in urban airspaces.
3. REQUIREMENTS FOR URBAN AIR MOBILITY
OPERATIONS
Requirements for UAM systems can be categorized into five
points. A large part, which will especially be relevant for
certification, are safety guarantees. There are several safety
considerations which aid in tackling safety concerns. Fur-
ther, the systems need to scale well with different types and
sizes of aircraft. This especially applies to the performance
of the aircraft regarding their avionics architecture. A mod-
ular avionics design facilitates their application in different
types of aircraft. Likewise, aircraft need to have interoper-
ability in the complex system of systems information web
for collision avoidance and air-ground communication. This
information web is located in an urban environment near
ground stations which leads to heightened security con-
cerns. These conditions make aircraft operating in urban
environments particularly susceptible to attacks. The five
requirements safety, scalability, performance, interoperabil-
ity, and cybersecurity will be discussed in more detail in the
next subsections. At the end of each subsection, the partic-
ular requirement that needs to be met to achieve airworthi-
ness for UAM is defined in the form of a recommendation.
3.1. Safety
Safety in the domain of aviation can be defined as the state
of being safe from harm or danger during the operation of
an aircraft. Safety is a significant factor in the develop-
ment and use of aircraft. The aviation industry remains the
leading force in driving rigid safety standards for transporta-
tion. Some recent reports covering the topic are Ref. 26–28.
The operating conditions of UAM systems give additional
significance to the discussion of safety. The current indus-
try vision is for UAS to operate in urban airspace which is
crowded, accompanied by a high frequency of passengers,
and which requires increased takeoffs and landings, as partly
discussed in Ref. 22.
Some of the challenges in terms of safety for UAM are
discussed in Ref. 6,29. Specifically the question emerges
how new technology concepts for UAM, such as simplified
flight controls or automated subsystems, can be assessed for
safety. The aircraft systems covering the aircraft itself, the
pilot, flight controls, avionics, and so forth need to be eval-
uated with new integrated evaluation methods. UAS are
envisioned to operate along with the full range of manned
and unmanned aircraft currently found in the airspace, pos-
sessing different capabilities and operating under specific
rules (Ref. 30). In addition to the high-density traffic sce-
narios, fully automated AI-based applications and ground
segment events with direct impact on the flight operations
will assume a role in UAM. In Ref. 31, EASA proposes a
general qualitative approach from Annex C and Annex D
of their Specific Operations Risk Assessment to tackle the
lack of safety data and field experience for manned and un-
manned aircraft operated in the U-space1airspace. Accord-
ing to Ref. 32, however, these methodologies currently do
not suffice to cover safety assessments for the operational
domain and previously mentioned operating conditions.
Specific examples for operating challenges of UAS are for
instance their restrictions to limited airspace, as described
in Ref. 33. Aircraft cannot enter forbidden airspace, which
could, for instance, be avoided with geofencing. The lim-
ited space in urban areas alongside the crowded airspace will
make precise and safe fencing of aircraft a challenging task.
Another example is the heavy influence of weather condi-
tions on the motion stability of UAM technologies such as
VTOL, as discussed in Ref. 34. The authors stress the ne-
cessity of thorough testing for safety certification of future
UAM technologies. Ref. 35 suggests that operational cer-
tificates for UAS operating under low or moderate airspeed
conditions will be carried out similar to the 14 CFR Part 135
certification (Ref. 36). Methodologies aiding in the testing
and certification process for UAM technologies are for in-
stance scenario-based testing and the precise definition of
the systems’ adaptive operational design domain (Ref. 37).
Regulatory frameworks for the certification of safe and air-
worthy UAS are still in their infancy. The earliest rules
for operation of urban aircraft have been published by
EASA in June 2022 in their Notice of Proposed Amendment
(Ref. 38). The regulatory framework for the operation of
drones covers objectives to ”ensure a high and uniform level
of safety for UAS subject to certification [...]” and ”enable
1As defined by the European Comission: ”U-space is the European
term used for Unmanned [or Urban] Traffic Management (UTM), a set
of new services relying on a high level of digitalisation and automation
of functions, and specific procedures designed to support safe, efficient
and secure access to airspace for large numbers of drones.”
49th European Rotorcraft Forum 2023
3
CC BY-SA 4.0
operators to safely operate manned VTOL-capable aircraft
[...]”. Other publications from regulatory organizations for
aviation, such as Ref. 39 from the International Civil Avi-
ation Organization or Ref. 40 from FAA, can be seen as
more general guidances. Other noteworthy documents are
EASA’s means of compliance with VTOL (Ref. 9) and com-
mission implementing regulations 2021/664, 2021/665, and
2021/666 (Ref. 41–43) with requirements for the air traf-
fic management and manned aviation operating in U-space
airspace. With increasing maturity of UAM, more regula-
tory frameworks with safety and certification considerations
can be expected.
In the context of safety, UAM shall adhere to a comprehen-
sive set of regulations and guidelines to ensure the highest
level of safety for passengers, operators, and the general
public.
3.2. Scalability
Scalability refers to ”the ability of a system to maintain
its performance and function, and to retain all its desired
properties when its scale is increased greatly, without caus-
ing a corresponding increase in the system’s complexity”
(Ref. 44). To operate UAS, scalability is a vital aspect
that aircraft operators need to consider. As demand grows,
they must quickly and proficiently scale up their operations,
which involves expanding the fleet, infrastructure, air traffic
management systems, and logistical aid to ensure smooth
operations. UAS are designed to thrive in densely popu-
lated urban areas with high traffic volume, which poses a
challenge in handling numerous flights and passengers while
maintaining safety and efficiency.
Architecturally, common system components of future
UAM systems need to scale well with different aircraft
types. Envisioned are UAM systems which serve different
purposes. Examples are urban air taxis or urban medical
aircraft. These aircraft have different capabilities, never-
theless, safety requirements should be applicable to all of
them, independent of their size and functionality. Two of
NASA’s concept aircraft are shown in Figure 1as reference.
The Tiltduct (left) and Multi-Tiltrotor (right) vehicles are
fundamentally different aircraft. Nevertheless, the systems
components and the aircraft themselves need to scale well
in the urban environment they operate in. Solutions for
the avionics architectures shall be effective in the sense
that the required functionalities for UAM can be achieved.
At the same time the systems are under the constraint of
efficiency in the sense that the execution of functionalities
is performant independent of the type of application.
Standardizing the necessary safety regulations and certifica-
tions for different UAS with highly variable operational sce-
narios to achieve the technologies’ airworthiness can pose
a challenge. Current safety standards applicable to conven-
Figure 1: Selection of NASA’s concept aircraft for UAM
(Ref. 45)
tional aircraft assume relatively mature and consistent op-
erations and procedures. The environment for future UAM
technologies, with an increased density of aircraft and po-
tentially unforeseeable flight scenarios, requires a precise
and partially new definition of standards.
Some of the challenges for pilots operating with UAM tech-
nologies are presented in Ref. 46. With the introduction of
automation systems such as AI-based applications for au-
tonomous flight, personnel operating future UAS face addi-
tional load during system operation. In addition, operating
different aircraft with changing operational conditions will
add to the operational complexity and make scalability in
terms of system utilization harder.
In the context of scalability, UAM shall possess the capac-
ity to seamlessly accommodate a significant increase in de-
mand and effectively handle a growing number of users,
infrastructure, and services without compromising safety,
efficiency, or overall performance. This includes the ability
to efficiently scale up operations, infrastructural support,
and technological capabilities in order to meet the evolving
needs of an expanding urban air transportation system.
3.3. Performance
Performance refers to the resource-efficiency of UAS for
their intended use and its implication in the type of systems
used for propulsion, computation, and so forth. A signifi-
cant issue for discussion for applications such as urban air
taxis is the economy within their scope of application. An
example is the avionics system, which plays a crucial role in
the development of performant UAS. Distributed Integrated
Modular Avionics (DIMA) architectures pose the preferred
choice for avionics systems in UAS. DIMA is an avionics ar-
chitecture concept in which several processing nodes are
placed throughout an aircraft. Each processing node is
responsible for specific functions and communication with
other nodes which are integrated via a high-speed digital
network, typically an avionics full-duplex switched Ethernet
(AFDX) network. Not only their high performance in the
scope of function execution but also the decreased number
of required components and therefore reduction in weight
makes DIMA favorable (Ref. 47).
49th European Rotorcraft Forum 2023
4
CC BY-SA 4.0
As discussed in Ref. 20, the demand for low noise emissions
and the willingness to pay are significant factors for public
acceptance and the success of UAM vehicles. Other factors
are the restrictions caused by weather, time of day, and ca-
pacity restrictions by urban infrastructure. Electric propul-
sion shows high potential for use in UAM technologies, tack-
ling some of the demands mentioned above. UAS are by
nature sensitive to vibrations and require a lightweight de-
sign. Electric propulsion with fewer moving parts, reduced
noise, and being suitable for lightweight vehicles represents
a superior solution for UAM (Ref. 48), compared to conven-
tional propulsion such as turbine. Still, further development
is needed to support the high performance and functionality
requirements existing in UAM (Ref. 49).
The development of new network technologies is a major
focus of the aviation industry, and Avionics Wireless Net-
works (AWN) is a significant part of this effort. Wireless
networks play a crucial role in the transportation industry
by reducing the amount of wiring needed in vehicles, thus
decreasing weight and increasing efficiency, resulting in sig-
nificant cost savings (Ref. 50). In particular, the aviation in-
dustry benefits from technologies such as Wireless Avionics
Intra-Communication (WAIC), which simplify wire installa-
tion and promote safety-critical concepts such as dissimilar
component redundancy and improved system reconfigura-
bility (Ref. 51,52). Features such as route segregation
and redundant radio links ensure dissimilar redundancy and
help to mitigate risks of single points of failure (Ref. 51).
One possible application of WAIC is for spatially distributed
controllers, actuators, and sensors, replacing current field-
bus technologies (Ref. 52). Network technologies used in
next generation UAS are discussed in detail in Ref. 15. With
the increase in digital and wireless system solutions in fu-
ture aircraft such as VTOLs, there will, however, also be an
increase in cybersecurity demands.
In the context of performance, UAM shall provide efficient
transportation solutions, with reduced travel times and in-
creased accessibility, enabling swift and convenient urban
mobility. UAM should demonstrate minimal environmental
impact, with the adoption of sustainable technologies and
practices.
3.4. Cybersecurity
As defined by the International Air Transport Association
in Ref. 53, “aviation cyber security may be considered as
the convergence of people, processes, and technology that
come together to protect civil aviation organizations, op-
erations, and passengers from digital attacks.” The prox-
imity of urban aircraft to ground stationed attackers and
the adoption of new communication technologies, such as
WAIC, make the systems more susceptible to cyberattacks.
Tackling these problems in the already heightened safety-
critical environment these technologies operate in will be a
demanding endeavour. This is particularly apparent when
identifying the data links in the UAM environment, as illus-
trated in Figure 2.
USS 1 USS 2
Distributed C2
5G
Vehicle-to-Vehicle
Communication
Augmented
Navigation
Direct
C2
Inter-USS
Comm.
C2
C2
Positioning
Figure 2: Urban aircraft system communication and data
links (Ref. 54,55)
Additionally to the existing data links found in commercial
aviation, there are supplementary communication networks
in UAM. Some of the core technologies found in future
UAM systems are augmented navigation with Command
and Control (C2)2links, as well as Unmanned Aircraft Sys-
tems Service Supplier (USS)3. Common vulnerabilities of
the systems, which need to be addressed for safety regula-
tions and certifiability, are jamming – interrupting targeted
RF signals, spoofing – sending of illegitimate information,
interception – manipulating video transmission, and Denial
of Service (DoS) – undermining controls and transmission
(Ref. 58). All of these threats are magnified due to ad-
vancements in internet connectivity of aircraft over the years
and the proximity of UAS to urban spaces and ultimately
ground attackers. Some of the current research areas for
the operational environment of UAM technology which are
relevant for cybersecurity are communication, navigation,
and surveillance. The development of more robust vehicle
2As defined in Ref. 56: ”Command and Control (C2) datalink is the
element of the command and control function that provides the inter-
face between the [Remotely Piloted Aircraft] (RPA) and the Ground
Control Station for the purposes of commanding and controlling the
flight.”
3As defined in Ref. 57: ”A USS is an entity that provides services
to support the safe and efficient use of airspace by providing services
to the operator in meeting [Unmanned Aircraft System Traffic Man-
agement] (UTM) operational requirements.”
49th European Rotorcraft Forum 2023
5
CC BY-SA 4.0
designs for UAM which can manage cybersecurity threats
will be of high priority (Ref. 30,59).
In the context of cybersecurity, UAM shall prioritize the
implementation of robust and comprehensive security mea-
sures to ensure the safe and secure operation of aerial trans-
portation systems. This includes secure communication,
intrusion detection and prevention, and secure software de-
velopment.
3.5. Interoperability
Interoperability refers to the seamless ability of distinct sys-
tems to function together, even when they are developed
and constructed by divergent organizations. In the context
of UAM, interoperability is crucial in ensuring that various
UAM systems and vehicles can safely and efficiently com-
municate with each other, share data, and coordinate their
operations. Figure 3illustrates the crammed airspace and
need for seamless interoperability for different types of air-
craft in a UAM scenario. In the presented scenario, drones
and other small unmanned vehicles operate in the low-level
airspace up to 150 m. Between 150 m and 2 km, VTOLs for
UAM operate in different zones in the UAM corridor. The
commercial airspace for airplanes is between 2 and 8 km.
The figure shows a UAM corridor with a vertical passing
zone for UAM vehicles. However, a horizontal passing zone
is also conceivable. Vertical and horizontal passing zones in
UAM corridors are described in Ref. 40 in more detail.
Interoperability is highly significant for UAM for several rea-
sons. First, UAM systems and vehicles need to communi-
cate with one another in real-time, requiring a high level of
data exchange and coordination to avoid collisions and other
safety risks. Second, guaranteeing interoperable aircraft can
enhance the efficacy of UAM systems by streamlining their
operations, reducing delays, and increasing their reliability.
Last, an interconnected system can help ensure that aircraft
remain accessible and affordable by creating a more open
and competitive market, which can lower costs and increase
the availability of UAM services in various regions.
To address the need for interoperability in UAM, several
initiatives and projects are underway worldwide, including:
•The development of standards and protocols for UAM
systems, created by aviation regulatory bodies such as
EASA and FAA.
•New testing and certification programs for UAM vehi-
cles and systems to ensure that they function together
safely and effectively.
•New partnerships and collaborations between different
UAM organizations, companies, and regulators with
the aim of promoting greater communication, infor-
mation sharing, and interoperability within the UAM
industry.
As described in Ref. 61, two fundamental obstacles need to
be tackled for the safe and reliable development of interop-
erable aircraft in urban environments:
(a) Operation planning for aircraft guaranteeing safety and
performance, and
(b) real-time airborne collision avoidance for an elevated
number of aircraft sharing the airspace without a priori
approval of all flight plans.
Specifically when talking about collision avoidance systems
and air-ground communication between humans and/or air-
craft in urban and crowded airspaces, the interoperability
of subsystems will play a crucial role in the adoption of
UAM technologies. Standardized hardware and software
systems will have the potential to increase operability of dif-
ferent types of aircraft in urban environments. The smaller
airspace margins as well as aircraft sizes and the need for
higher maneuverability in urban airspaces will call for com-
putationally performant avionics solutions (Ref. 25).
In the context of interoperability, UAM shall adhere to a
set of requirements to ensure seamless integration and ef-
fective collaboration among various stakeholders involved
in the operation and management of urban air transport
systems. These requirements encompass standardized pro-
tocols, compatibility with existing infrastructure, and inte-
gration of systems and services.
4. PUTTING IT ALL TOGETHER
Five major requirements for accomplishing operations of
UAS have been identified. They are safety, scalability,
performance, cybersecurity, and interoperability. These re-
quirements are highly interdependent and crucial for achiev-
ing airworthiness for future UAS.
One of the key findings of this paper is that safety is a
critical requirement for UAS due to their operation in urban
environments with high population densities. Therefore,
advanced safety features such as hazard analysis techniques
need to be incorporated into the avionics systems to ensure
safe operation. Another key finding is that scalability is an
important feature that future urban aircraft need to fulfill.
The systems need to scale well with different types and
sizes of aircraft. Technological advancements, particularly
in batteries and electric as well as distributed propulsion
systems, are of high importance. They facilitate the design
of novel aircraft types with VTOL capabilities and tackle
some of the aforementioned requirements.
One interpretation of these findings is that the targeted de-
velopments for UAM are a complex and challenging task
that requires a multidisciplinary approach. The interdepen-
dence of the presented requirements highlights the need for
a holistic approach to UAS development that takes into ac-
count the unique operating conditions of UAM. Achieving
49th European Rotorcraft Forum 2023
6
CC BY-SA 4.0
PASSING ZONE
VERTIPORT VERTIPORT SUBURBCITY
50
150
2000
< 8000
height in m
UAM
Corridor
Low-Level
Airspace
Commercial
Airspace
Figure 3: UAM scenario with different types of aircraft operating in and above cities and suburbs (Ref. 40,60)
airworthiness and acceptance for UAM will enable the safe
and efficient operation of urban aircraft, which have the
potential to revolutionize urban mobility.
5. CONCLUSION
In recent years, the concept of UAM has garnered consid-
erable interest as a rapidly developing field. UAM aims
to make air travel accessible within urban areas, offering
fast and efficient transportation of people and goods while
simultaneously alleviating congestion on the ground. This
technology has the potential to revolutionize urban mobility
by providing more sustainable and quicker transport solu-
tions. Overall, the emergence of new technologies such as
UAM offers solutions to some of the current challenges in
transportation. However, the adoption of these technolo-
gies also adds additional constraints to their aircraft devel-
opment. Five major requirements have been identified for
the development of UAS, namely safety, scalability, perfor-
mance, cybersecurity, and interoperability. As presented,
the areas are highly interdependent and need to be thor-
oughly researched to achieve airworthiness for future UAS.
One limitation of this paper is that it does not provide de-
tailed information for some of the challenges and solutions
to the deployment of UAM. Further research is needed to
identify and address these points, and achieve a full tech-
nical coverage of necessary requirements for UAM. Within
the scope of this research more detailed specifications for
the development needs of UAM technologies will be inves-
tigated.
49th European Rotorcraft Forum 2023
7
CC BY-SA 4.0
References
1. Chana, W.F., A. Flying Automobiles: Are They for
Real? https://books.google.de/books?id=pqT%
5C_xwEACAAJ (AIAA, 1996).
2. Bryan, F. Beyond the Model T: The Other Ventures of
Henry Ford isbn: 9780814322369. https://books.
google.de/books?id=DMu1AAAAIAAJ (Wayne State
University Press, 1990).
3. James R. Chiles. Flying Cars Were a Dream That
Never Got Off the Ground https://books.google.
de/books?id=pqT%5C_xwEACAAJ (AIAA, Feb. 1989).
4. Leary, W. M. Robert Fulton’s Skyhook and Opera-
tion Coldfeet. CENTRAL INTELLIGENCE AGENCY
WASHINGTON DC CENTER FOR THE STUDY OF
INTELLIGENCE. https://www. cia.gov/static/
Robert - Fulton- Operation - Coldfeet. pdf (Jan.
1995).
5. Fedrigo, D. F. G., Gobato, R. & Gobato, A. Avro-
car: a real flying saucer 2015. arXiv: 1507 . 06916
[physics.pop-ph].
6. Cohen, A. P., Shaheen, S. A. & Farrar, E. M. Ur-
ban Air Mobility: History, Ecosystem, Market Poten-
tial, and Challenges. IEEE Transactions on Intelligent
Transportation Systems 22, 6074–6087. https : / /
doi.org/10.1109/TITS.2021.3082767 (2021).
7. Petit, Y. L. & Islam, K. Urban Mobility Next 8, Ex-
pectations and success factors for Urban Air Mobil-
ity in Europe tech. rep. (European Institute of Inno-
vation & Technology, Nov. 2022). https : / / www .
eiturbanmobility . eu / wp - content / uploads /
2022/11/EIT-UrbanAirMobility.pdf.
8. Federal Aviation Administration. UAS Integration
Pilot Program (2017). https : / / www . faa . gov /
uas / programs _ partnerships / completed /
integration_pilot_program.
9. European Union Aviation Safety Agency. Special Con-
dition for VTOL and Means of Compliance (June
2023). https : / / www . easa . europa . eu / en /
document - library / product - certification -
consultations/special-condition-vtol.
10. Radio Technical Commission for Aeronautics. Ad-
vanced Air Mobility (AAM) (2023). https: //www.
rtca.org/about/technical-initiatives-aam/.
11. Urban air mobility: A comprehensive review and com-
parative analysis with autonomous and electric ground
transportation for informing future research. Trans-
portation Research Part C: Emerging Technologies
132, 103377. issn: 0968-090X. https://doi.org/
10.1016/j.trc.2021.103377 (2021).
12. Schweiger, K. & Preis, L. Urban Air Mobility: Sys-
tematic Review of Scientific Publications and Regu-
lations for Vertiport Design and Operations. Drones
6. issn: 2504-446X. https: //doi .org/ 10.3390 /
drones6070179 (2022).
13. McKinsey & Company. Study on the societal accep-
tance of Urban Air Mobility in Europe tech. rep. (Eu-
ropean Union Aviation Safety Agency, May 2021).
https:/ / www . easa.europa.eu / en / downloads/
127760/en.
14. Volocopter. PIONEERING THE URBAN AIR
TAXI REVOLUTION (June 2019). https :
/ /www . volocopter. com /wp - content/ uploads /
Volocopter-WhitePaper-1-01.pdf.
15. Cullen, M., Moore, R., Schlosser, C. & Benton, M.
Connecting The Future of Flight White Paper tech.
rep. (TTI TE Connectivity, 2021). https : / / www .
ttieurope . com / content / dam / tti - europe /
resources / Literature / SupplierGuides / TTI -
TE-Connecting- The- Future-of-Flight- White.
pdf.
16. Johnny T. Doo and Michael A. Tsairides and Marilena
D. Pavel and Michael Smith and Arnaud Didey and
Edward Bennet and Craig Hange and Michael Brom-
field and Nathan P. Diller and Jessie Mooberry. NASA
Electric Vertical Takeoff and Landing (eVTOL) Air-
craft Technology for Public Services – A White Paper
tech. rep. (National Aeronautics and Space Admin-
istration, Sept. 2021). https://ntrs.nasa. gov /
api/ citations /20205000636/downloads / 2021-
08-20-eVTOL-White-Paper-Final_V48.pdf.
17. Vertical Aerospace et al. The Future of Advanced
Aerial Mobility tech. rep. (Vertical Aerospace, Oct.
2021). https :/ / vertical- aerospace . com/ wp -
content / uploads / 2021 / 10 / The - Future - of -
Advanced-Aerial-Mobility.pdf.
18. EHang. White Paper on Urban Air Mobility Systems
(Jan. 2020). https:/ / www . ehang . com /app/ en /
EHang% 20White%20Paper %20on%20Urban%20Air%
20Mobility%20Systems.pdf.
19. Kay Pl¨otner and Anna Straubinger and Lukas Preis
and Michael Shamiyeh. Putting Urban Air Mobil-
ity into perspective tech. rep. (Bauhaus Luftfahrt,
June 2023). https : / / www . ehang . com / app / en /
EHang% 20White%20Paper %20on%20Urban%20Air%
20Mobility%20Systems.pdf.
20. Straubinger, A. et al. An overview of current research
and developments in urban air mobility – Setting the
scene for UAM introduction. Journal of Air Transport
Management 87, 101852. issn: 0969-6997. https:
49th European Rotorcraft Forum 2023
8
CC BY-SA 4.0
//doi.org/10.1016/j.jairtraman.2020.101852
(2020).
21. On the understanding of the current status of urban air
mobility development and its future prospects: Com-
muting in a flying vehicle as a new paradigm. Trans-
portation Research Part E: Logistics and Transporta-
tion Review 166. https://doi.org/ 10.1016 /j.
tre.2022.102868 (2022).
22. Vascik, P. D., Balakrishnan, H. & Hansman, R. J. As-
sessment of Air Traffic Control for Urban Air Mobility
and Unmanned Systems in 8th International Confer-
ence for Research in Air Transportation (ICRAT) (MIT
International Center for Air Transportation (ICAT),
June 2018). http : / / hdl . handle . net / 1721 . 1 /
117686.
23. Reiche, C., McGillen, C., Siegel, J. & Brody, F. Are
We Ready to Weather Urban Air Mobility (UAM)?
in 2019 Integrated Communications, Navigation and
Surveillance Conference (ICNS) (2019), 1–7. https:
//doi.org/10.1109/ICNSURV.2019.8735297.
24. Stelkens-Kobsch, T. H. & Predescu, A.-V. Contribu-
tion to a secure urban air mobility in 41st IEEE/AIAA
Digital Avionics Systems Conference, DASC 2022
(Oct. 2022). https://elib.dlr.de/191044/.
25. Athavale, J., Baldovin, A., Mo, S. & Paulitsch, M.
Chip-Level Considerations to Enable Dependability for
eVTOL and Urban Air Mobility Systems in 2020
AIAA/IEEE 39th Digital Avionics Systems Conference
(DASC) (2020), 1–6. https://doi.org/10.1109/
DASC50938.2020.9256436.
26. Debyser, A. AVIATION SAFETY tech. rep. (European
Parliament, Mar. 2022). http : / / www . europarl .
europa.eu/ftu/pdf/en/FTU_3.4.9.pdf.
27. Safety Intelligence & Performance Department.
ANNUAL SAFETY RECOMMENDATIONS REVIEW
tech. rep. (European Union Aviation Safety Agency,
Sept. 2022). https://doi.org/10.2822/199328.
28. Operations, Safety and Security. 2021 Safety
Report tech. rep. (International Air Trans-
port Association, Apr. 2021). https :
/ / www . iata . org / contentassets /
bd3288d6f2394d9ca3b8fa23548cb8bf / iata _
safety_report_2021.pdf.
29. Holbrook, J. et al. Enabling Urban Air Mobility:
Human-Autonomy Teaming Research Challenges and
Recommendations in AIAA AVIATION 2020 FORUM
(2020). https://doi.org/10.2514/6.2020-3250.
30. Thipphavong, D. P. et al. Urban Air Mobility Airspace
Integration Concepts and Considerations in 2018 Avi-
ation Technology, Integration, and Operations Confer-
ence (June 2018). https://doi .org/10.2514/6.
2018-3676.
31. European Union Aviation Safety Agency. High-level
regulatory framework for the U-space (Mar. 2020).
https:/ / www . easa.europa.eu / en / downloads/
111303/en.
32. Castro, D. G. & Garc´ıa, E. V. Safety Challenges for
Integrating U-Space in Urban Environments in 2021
International Conference on Unmanned Aircraft Sys-
tems (ICUAS) (2021), 1258–1267. https : / / doi .
org/10.1109/ICUAS51884.2021.9476883.
33. Schuchardt, B. I. et al. Air Traffic Management as
a Vital Part of Urban Air Mobility - A Review of
DLR’s Research Work from 1995 to 2022. Aerospace
10. issn: 2226-4310. https://doi.org/10.3390/
aerospace10010081 (2023).
34. Takacs, A. & Haidegger, T. Infrastructural Require-
ments and Regulatory Challenges of a Sustainable
Urban Air Mobility Ecosystem. Buildings 12.
issn: 2075-5309. https : / / doi . org / 10 . 3390 /
buildings12060747 (2022).
35. Graydon, M., Neogi, N. A. & Wasson, K. Guidance
for Designing Safety into Urban Air Mobility: Haz-
ard Analysis Techniques in AIAA Scitech 2020 Forum
(Jan. 2020). https://doi.org/10.2514/6.2020-
2099.
36. Code of Federal Regulations. PART 135 - OPER-
ATING REQUIREMENTS: COMMUTER AND ON
DEMAND OPERATIONS AND RULES GOVERN-
ING PERSONS ON BOARD SUCH AIRCRAFT (Feb.
2023). https: //www.ecfr .gov/current/ title-
14/chapter-I/subchapter-G/part-135.
37. Girija, A. A., Stefani, T., Mut, R., Kr¨uger, T. & Du-
rak, U. USING OPERATIONAL DESIGN DOMAIN
FOR SAFE AI IN URBAN AIR MOBILITY in ASAM
International Conference 2022 (Nov. 2022). https:
//elib.dlr.de/192568/.
38. European Union Aviation Safety Agency. Notice of
Proposed Amendment 2022-06 (June 2022). https:
//www.easa.europa.eu/en/downloads/136705/
en.
39. International Civil Aviation Organization. LEGAL
AND SOCIETAL STAKES FOR THE EMERGING
AIR MOBILITY IN METROPOLITAN AREAS (Aug.
2022). https://www . icao . int / Meetings / a41 /
Documents/WP/wp_110_rev_en.pdf.
40. Federal Aviation Administration. Urban Air Mobil-
ity (UAM) Concept of Operations. https : / / www .
faa . gov / sites / faa . gov / files / Urban %
49th European Rotorcraft Forum 2023
9
CC BY-SA 4.0
20Air % 20Mobility % 20(UAM ) %20Concept % 20of %
20Operations%202.0_0.pdf (May 2023).
41. European Union Aviation Safety Agency. COM-
MISSION IMPLEMENTING REGULATION (EU)
2021/664 (Apr. 2021). https://eur-lex.europa.
eu / legal - content / EN / TXT / ?uri = CELEX %
3A32021R0664.
42. European Union Aviation Safety Agency. COM-
MISSION IMPLEMENTING REGULATION (EU)
2021/665 (Apr. 2021). https://eur-lex.europa.
eu / legal - content / EN / TXT / ?uri = CELEX %
3A32021R0665.
43. European Union Aviation Safety Agency. COM-
MISSION IMPLEMENTING REGULATION (EU)
2021/666 (Apr. 2021). https://eur-lex.europa.
eu / legal - content / EN / TXT / ?uri = CELEX %
3A32021R0666.
44. IFAR, A. W. G. et al. Scientific Assessment for Urban
Air Mobility (UAM) tech. rep. (Mar. 2023). https:
//elib.dlr.de/195379/.
45. Whiteside, S. & Pollard, B. Conceptual Design of
a Tiltduct Reference Vehicle for Urban Air Mobility.
Aeromechanics for Advanced Vertical Flight. not yet
published (Jan. 2022).
46. Bauranov, A. & Rakas, J. Urban air mobility
and manned eVTOLs: safety implications in
2019 IEEE/AIAA 38th Digital Avionics Systems
Conference (DASC) (Sept. 2019), 1–8. https :
//doi.org/10.1109/DASC43569.2019.9081685.
47. Annigh¨ofer, B. Model-based Architecting and Opti-
mization of Distributed Integrated Modular Avionics
isbn: 9783844034202 (Shaker Verlag, Aachen, 2015).
48. Patterson, M. D., Antcliff, K. R. & Kohlman, L. W.
A Proposed Approach to Studying Urban Air Mobil-
ity Missions Including an Initial Exploration of Mission
Requirements in AHS International 74th Annual Fo-
rum & Technology Display (2018).
49. Markov, A. A Framework for Integrating Advanced
Air Mobility Vehicle Development, Safety and Certifi-
cation Dissertation (Georgia Institute of Technology,
May 2022). http://hdl.handle.net/1853/66598.
50. Elgezabal G´omez, O. Fly-by-wireless: Benefits, risks
and technical challenges in CANEUS Fly by Wireless
Workshop 2010 (2010), 14–15. https://doi.org/
10.1109/FBW.2010.5613788.
51. Uwe Schwark. Wireless Avionics Intra-Communication
(WAIC) https : / / www . sae . org / binaries /
content / assets / cm / content / attend / 2017 /
aerospace - standards - summit / waic . pdf. SAE
Aerospace Standards Summit Spring 2017. Apr. 2017.
52. Lukic, B., Ahlbrecht, A., Friedrich, S. & Durak, U.
State-of-the Art in Engineering Integrated Modular
Avionics and the Way Ahead in 42nd IEEE/AIAA Dig-
ital Avionics Systems Conference, DASC 2023, not yet
published (Oct. 2023).
53. International Air Transport Association. Avi-
ation Cyber Security (May 2020). https :
/ / www . iata . org / contentassets /
e55ae27b2fc34343a1143fca5129c8dd/aviation-
cyber-security-position.pdf.
54. Johnson, R. D. Unmanned Aircraft System Traffic
Management (UTM) Project in (2018).
55. Bae, J., Lee, H. & Lee, H. A Study on Communication
Technologies for Urban Air Mobility in 2022 13th In-
ternational Conference on Information and Communi-
cation Technology Convergence (ICTC) (2022), 2235–
2240. https : / / doi . org / 10 . 1109 / ICTC55196 .
2022.9952749.
56. European Union Aviation Safety Agency. SC-
RPAS.C2, RPAS Command and Control (C2)
Datalink tech. rep. (May 2016). https : / / www .
easa.europa.eu/en/downloads/20784/en.
57. Joseph L. Rios and Irene S. Smith and Priya Venkate-
sen and Jeffrey R. Homola and Marcus A. Johnson
and Jaewoo Jung. UAS Service Supplier Specifica-
tion tech. rep. (National Aeronautics and Space Ad-
ministration, Oct. 2019). https : / / ntrs . nasa .
gov / api / citations / 20200000512 / downloads /
20200000512.pdf.
58. Tang, A. C. A Review on Cybersecurity Vulnerabilities
for Urban Air Mobility in AIAA Scitech 2021 Forum
(2021). https://doi.org/10.2514/6.2021-0773.
59. Jordan, A. et al. Systematic Evaluation of Cybersecu-
rity Risks in the Urban Air Mobility Operational Envi-
ronment in 2022 Integrated Communication, Naviga-
tion and Surveillance Conference (ICNS) (2022), 1–
15. https://doi.org/10.1109/ICNS54818.2022.
9771507.
60. Shrestha, R., Oh, I. & Kim, S. A Survey on Opera-
tion Concept, Advancements, and Challenging Issues
of Urban Air Traffic Management in Frontiers in Fu-
ture Transportation (2021).
61. Rodionova, A., Pant, Y. V., Jang, K., Abbas, H. &
Mangharam, R. Learning-to-Fly: Learning-based Col-
lision Avoidance for Scalable Urban Air Mobility 2020.
https://doi.org/10.48550/ARXIV.2006.13267.
49th European Rotorcraft Forum 2023
10
CC BY-SA 4.0
