By Ir Steven LUI, Ir Andy CHAN, Dr Seakay XIE, Mr Hirofumi SAITO, Mr Evan LUK, and Mr Jacob LOUIE of AECOM Asia Co. Ltd.
Electric Vertical Take-off and Landing (eVTOL) (image courtesy of EHang)
The convergence of the need for travel efficiency and the desire for environmental sustainability has brought us closer than ever to realising a dream that was once—merely a decade ago—considered idealistic. Flying cars, set to disrupt conventional travel methods, are on the horizon. This game-changing innovation takes the form of electric Vertical Take-off and Landing (eVTOL) aircraft.
Advanced Air Mobility (AAM) is an emerging concept that leverages safe, automated, electric, and accessible air transportation system for passenger, cargo, and other operations. As a subset of AAM, Urban Air Mobility (UAM) focuses on operations within the urban environment. With the advancement of Distributed Electric Propulsion (DEP) technology, eVTOL aircraft represents a highly promising solution for transportation in the future. Positioned between drones, helicopters, and conventional aircraft, eVTOLs offer a unique combination of features for efficiently transporting humans and goods.
Although the designs of eVTOL aircraft vary, they do share a few key features with helicopters. Both eVTOLs and helicopters can perform vertical take-off and landings (VTOL), which allows them to operate without extensive infrastructure such as long runways. With the cruise speed typically exceeding 200 km/h, they can travel point-to-point on a pre-defined flight route, avoiding road congestion and capitalising on available airspace. However, eVTOLs possess several distinct advantages over helicopters. Unlike helicopters, which rely on internal combustion engines, eVTOLs can be powered by fully electric or hybrid systems. This results in either zero or low carbon emissions during flight and significantly quieter operations. Additionally, DEP provides greater safety in the event that motor failure occurs. eVTOLs are designed to operate at vertiports/vertistops, which have the potential to be strategically located at buildings’ rooftops to improve the convenience for passengers. Furthermore, while eVTOLs are initially designed to be operated by pilots, they are expected to become autonomous as the autonomous technology matures. Given these advantages, eVTOLs are exceptionally well-suited for efficient and sustainable UAM operations.
Major players around the world
Back in 2017, there were only a handful of eVTOL models in the world. However, advancements in battery and electric motor technology have made eVTOLs a possibility. Today, we are witnessing a surge of interest in eVTOLs, with over 770 different concepts being developed worldwide. Aviation Week's AAM Baker's Dozen has identified the top companies that are highly likely to achieve certification, commercialisation, and high-volume production in the near future. These companies are ranked as follows: Joby, Archer, Volocopter, EHang, Beta, Eve, Lilium, Vertical, Airbus, Wisk, AutoFlight, Overair, and Supernal, representing a diverse range of countries and regions, including Mainland China, the US, Europe, and the Asia-Pacific. They are striving to achieve Type Certification of their eVTOL models with aviation regulatory authorities such as the Federal Aviation Administration (FAA), the European Union Aviation Safety Agency (EASA), and the Civil Aviation Administration of China (CAAC). Some are expected to launch commercial passenger service as early as 2025.
Notably, the eVTOL industry is rapidly gaining momentum in Mainland China. EHang’s EH216-S (a 2-seater with 35 km range) has secured the world’s first eVTOL Type Certificate, Airworthiness Certificate, and Production Certificate for their autonomous eVTOL from CAAC in October 2023, December 2023, and March 2024 respectively. This signifies its compliance with CAAC’s safety standards and airworthiness requirements, both in design and production, clearing the way for its use in commercial operations. On the other hand, AutoFlight’s five-seater Prosperity I and its cargo-variant, CarryAll V2000CG have achieved several remarkable milestones this year. In February 2024, Prosperity I completed a 50-km cross-strait trial flight between Shenzhen and Zhuhai. The company aims to provide an attractive, greener and faster transportation alternative connecting the Greater Bay Area (GBA) cities at affordable prices in the near future. Additionally, AutoFlight’s CarryAll obtained CAAC’s Type Certificate in March 2024 and completed a trial flight at Shanghai Pudong International Airport in May 2024. This trial flight marks the world’s first multi-tonne eVTOL flight at a 4F-rated airport, the highest airport rating, which handles large commercial aircraft.
Figure 1: AutoFlight CarryAll V2000CG’s trial flight and its flight path at Shanghai Pudong International Airport (Source: https://baijiahao.baidu.com/s?id=1798902850075532965&wfr=spider&for=pc)
Market size and time horizons
According to estimates by Morgan Stanley Research in 2021, the global total addressable market for UAM is projected to reach approximately US$1 trillion by 2040. Looking further, the estimate suggests that the market could expand to a staggering US$9 trillion by 2050, which would represent 5 to 6% of the projected global Gross Domestic Product (GDP) in 2050. In the foreseeable future, the adoption of eVTOLs planes is expected to follow a certain trajectory. For the coming five years, early adopters could offer limited premium eVTOL services, targeting specific high-end transportation needs. Over the next ten years, the adoption of eVTOL aircraft is projected to increase as more people become familiar with the technology's advantages. This growth in demand will be likely to drive the expansion of vertiport networks, providing additional take-off and landing locations for eVTOLs. However, during this phase, eVTOL services will still be priced as premium options, reflecting their exclusivity and unique capabilities. Looking ahead to the next fifteen years, the industry envisions the establishment of full network build-outs for UAM. This involves developing the necessary infrastructure, namely the air traffic management systems and wider vertiport networks, to support widespread eVTOL operations. As the industry matures and economies of scale come into play, the pricing model is expected to make transitions toward a desired equity model, resembling the concept of rideshare services. This shift would make eVTOL services more accessible and affordable to a broader range of individuals, increasing their resemblance to current rideshare pricing structures.
Potential applications in Hong Kong and GBA
The cruising range of eVTOLs varies by their design, size and intended use. Some eVTOL models are suitable for intra-city transport, while others could be used to serve inter-city transport needs. The following provides an illustration of the range of eVTOLs, demonstrating their ability to travel from Hong Kong to various other cities within the GBA on a single charge.
Figure 2: Distance range of various eVTOL models
When comparing the travel time of eVTOLs with that of conventional modes of transportation, eVTOLs’ advantages become apparent. For example, consider a journey from Central to the future San Tin Technopole. Riding on a taxi would require approximately one hour during peak hours. With eVTOL, the same journey could be completed within 10 minutes (over 80% time saved). For an inter-city case, Central to Foshan city would take approximately four hours by cross-border bus, but eVTOL could travel in approximately 40 minutes (over 80% time saved). These time savings could not only enhance the efficiency of daily travel but also improve productivity and quality of life for individuals. By offering faster and more convenient travel options, eVTOLs have the potential to revolutionise transportation and improve mobility for residents and visitors in Hong Kong.
Infrastructure design considerations
In working towards the successful implementation of this new technology, AECOM, a leading infrastructure consulting firm, has been collaborating closely with eVTOL industry stakeholders, including National Aeronautics and Space Administration (NASA), to establish vertiport standards and ensure safety compliance. Our expertise in integrating various components such as energy systems enables them to optimise eVTOL operations and facilitate the effective implementation of eVTOLs in urban landscapes, prioritising safety and operational efficiency.
For vertiport design, there are various key factors to be considered:
- Vertiport location for strategic integration of eVTOLs into existing transport network and inter-modal connectivity
- Vertiport size and layout, considering compatibility to accommodate different models of eVTOLs
- Spatial requirements and separation with other traffic (for example, conventional aircrafts, helicopters, drones) in the airspace through air traffic management (automated/semi-automated systems)
- Charging infrastructure and provision of power for eVTOLs’ charging needs
- Fire protection systems and other safety measures for emergencies
- Noise and environmental considerations (for example, migratory birds)
- Passenger experience for simplicity, speed and convenience
- Modular and adaptable designs for ability to scale as market matures (namely, provision for high-frequency operations)
- Physical security as well as cybersecurity against unauthorised access and potential threats
- Potential visual pollution and privacy concerns of eVTOL operations in urban areas
Although the rapid development of eVTOL and UAM technologies is a recent phenomenon, the FAA released the first vertiport design guidelines back in 1991. At that time, civil tiltrotor aircraft were considered a viable option for city-centre operations. However, they never became commercially viable due to various issues, including noise and safety concerns. Today, major aviation agencies have provided comprehensive vertiport design standards that different stakeholders can reference. These documents offer interim guidelines on vertiport layout, safety measures, lighting, markings, and environmental considerations, all essential for the efficient and safe operation of vertiports.
Although there are no official standards available yet for Mainland China, the China Civil Airports Association (中國民用機場協會) released an Association Standard (團體標準) for eVTOL vertiports in May 2024.
Figure 3: Engineering Brief #105 – Vertiport Design by the FAA
Figure 4: Prototype Technical Specifications for the Design of VFR Vertiports for Operation with Manned VTOL-Capable Aircraft Certified in the Enhanced Category (PTS-VPT-DSN) by the European Union Aviation Safety Agency (EASA)
Figure 5: Technical requirements for electric vertical take-off and landing aircraft (eVTOL) landing field (电动垂直起降航空器(eVTOL)起降場技術要求) by the China Civil Airports Association (CCAA)
These guidelines share many similarities, with only minor differences. For example, there are variations in the minimum dimensions for take-off and landing areas, as shown in Figure 6.
Figure 6: Comparison of minimum dimensions for take-off and landing area
Touchdown and Lift-off Area (TLOF): A load bearing, paved area designated for the touchdown or lift-off of eVTOL aircraft.
Final Approach and Take-off Area (FATO): A load bearing, paved area designated for eVTOL to perform the final phase approach and to initiate take-off.
Safety Area: An obstacle-free area surrounding the FATO, intended to reduce the risk of damage to aircraft accidentally diverging from FATO.
The D value generally refers to the diameter of the smallest circle enclosing the VTOL aircraft projection on a horizontal plane, when the aircraft is in the take-off or landing configuration and rotors are turning. The D value is considered for the largest eVTOL aircraft that the vertiport is expected to serve. For example, under the EASA standard, if the D value of the design eVTOL is 15 m, it would require 12.45 m x 12.45 m area for TLOF (non-elevated vertiport), 22.5 m x 22.5 m area for FATO, and provision of 3.75 m outside of FATO as Safety Area.
AECOM expertise and experience
As leaders in vertiport design, UAM, sustainable technologies, and transport planning, our team comprises global experts in multiple fields. AECOM designed a network of vertiports connecting strategic locations in major Florida cities. We have clients for eVTOL vertiport infrastructure not only in the USA, but also in cities across the Middle East and Asia.
As eVTOL technology continues to evolve, it is imperative for our government and other relevant stakeholders to adapt to its dynamic trajectory, especially since eVTOL is one of the core elements in the Low-altitude economy promoted by the Chinese government. In February 2024, the Shenzhen government implemented the nation’s first legal framework for promoting the Low-altitude Economy, and highlighted the need for developing infrastructure like vertiports. In August 2024, it also announced plans to construct its Low-altitude Infrastructure Network, comprising over 1,000 take-off and landing sites by the end of 2025. In addressing risks and considerations for developing vertiports, forerunning eVTOL enablers like AECOM aspire to provide safe, efficient, and sustainable transport solutions. Despite the challenges, we believe eVTOLs possess tremendous potential to revolutionise Hong Kong’s transport landscape and further advance the city as a smart city of tomorrow.
Figure 7: AECOM expertise and experience