Undoubtedly, aircraft certification remains the major milestone that needs to be reached before the commercial urban air mobility (UAM) trial at the 2024 Summer Olympic Games in Paris.
However, as frequently stated by many stakeholders, public acceptance will be one of the many tiles of the complex mosaic needed to establish and maintain regular UAM services in our cities. Some key components of this acceptance include feedback and permits required from a wide range of agencies and authorities, both at national and local levels.
On Sept. 7, 2023, the French Environmental Authority (Ae) published Opinion No. 2023-46 (in French) on the development of a vertiport on the Seine, Quai d’Austerlitz, one of the locations planned to be used by Volocopter for commercial demonstrations next summer. The main developer for the vertiport is international airport operator Group ADP, together with RATP Group, Paris’ public transport operator.
While the opinion is not binding and is neither favorable nor unfavorable, the opinion asks Groupe ADP to review some aspects of the analysis to quantify the effects of this project on the population, as well as the natural and urban environment, with some more detail.
Vehicle and commercial demonstration details
Additionally, the opinion gives us further insight to infer more details on the vehicle and planned operations, from extracts of the file that the developer would have submitted.
The location of the floating vertiport is now specified on the Quai d’Austerlitz, adjacent to the Cité de la Mode et du Design (City of Fashion and Design) building. The vertiport will be built on a platform measuring approximately 740 square meters (7,970 square feet). It will include a passenger check-in, waiting area, and a restroom. A battery charging locale will be housed in a converted cargo container.
The opinion also confirms some details on the aircraft itself. The D-value is given as 12 m (39 ft.) with a maximum takeoff weight of one imperial ton (2,200 pounds) and an operating temperature range between five degrees Celsius to 35C (41 degrees Fahrenheit to 95F). It is estimated that the aircraft will be heard for 25 seconds during overflight and 40 seconds during takeoff and landing phases. The cruising altitude is stated as 150 m (500 ft.).
The commercial demonstration is expected to span from May to December 2024. Flights will be operated between 8 a.m. and 6 p.m., with a maximum of three roundtrips per hour. About 5,000 movements are estimated for the duration of the demonstration’s stated timeframe. According to the submission, this could increase up to 14,700 movements.
The proposed vertiport at Quai d’Austerlitz lies within the P 23 Prohibited Area, located over central Paris from ground level up to 2,000 m (6,500 ft.). Normally, civil aircraft operations are not allowed in this area, and up to the time of the Ae opinion, the required permit from the Paris police prefecture was not in place for the commercial demonstration. Notably, the section of the route between the heliport at Issy-les-Moulineaux and the proposed vertiport that penetrates P 23 is part of an existing visual flight rules (VFR) helicopter route over the Seine and is used by emergency medical services helicopters to access Pitié-Salpêtrière hospital.
The Ae opinion then focuses on the following specific issues and provides some details on what information would be expected from the developer.
Acoustic impact
The acoustic impact of the project must be analyzed not only in the vicinity of the planned vertiport, but over the entire overflight route. The analysis submitted by the project leader states that up to 55 m (180 ft.) laterally from the route, the calculated acoustic contribution of the eVTOL over the ground is between 60 to 65 dB(A) but an illustration (Figure 4) submitted in the same file appears to show a higher value and should be clarified.
It also noted that the aircraft may not necessarily always fly on the centerline of the route, such as in the case of traffic separation schemes. This should be taken into consideration when delimiting the lateral extent of the noise footprint.
The Ae also noted that the background noise currently generated by vehicular road traffic is planned to decrease, with measures such as the recently introduced 30 kilometers per hour (18.6 miles per hour) speed limit in Paris’ city center, as well as a greater penetration of quieter electric ground vehicles. This will decrease the noise available to mask the eVTOL’s own noise signature. This expected evolution of background noise levels should be factored in the study.
Energy consumption and greenhouse gas emissions
The Ae recommends that the vehicle manufacturer, in this case Volocopter, should provide a balance sheet, including both vehicle construction and operation phases, considering the average emission factor of the French electricity production mix, and correcting the greenhouse gas emissions balance of the project by presenting the assumptions in detail.
When questioned by the Ae’s rapporteurs, the developer provided an estimate of 190 kWh/100 km for the vehicle. For comparison, the consumption of a thermal car is about 50 kWh/100 km, and that of an electric car is about 15 kWh/100 km. Paris’ subway’s energy use is estimated at six kWh/100 passenger km, about 30 times less than the consumption announced for Volocity.
Therefore, the Ae recommends specifying which mode of transport UAM will be complementing, to have a more representative like-with-like comparison. The Ae also voices some concern that the project’s overall energy usage runs counter to the multiannual energy consumption program plans.
Visual impact
One effect which is sometimes overlooked is the visual impact that these vehicles will have if they will be flying in large numbers over urban areas. The Ae points out that this may be more acute — as in this case, the flights will be in airspace that was mostly prohibited to civilian flights.
The recommendation is that the overflights should be considered as having a dynamic impact on the urban landscape and this aspect should be explicitly considered in the study. The Ae estimates that the number of movements between Issy-les-Moulineaux heliport and the proposed vertiport site will increase by a factor of 4.5, considering the annual recorded movements on these VFR routes during 2022.
Interaction with medical or emergency transport aircraft
As commercial demonstration flights on this vertiport pair will be using pre-existing helicopter routes, including the route to the helipad of the Pitié-Salpêtrière hospital, the priority of medical transport and other security flights on these corridors must be unambiguous. Although one would think this is a given, the Ae states that this must be considered in the overall assessment.
Conclusion
This opinion, by its own definition, is not a showstopper for the planned commercial trials next year. However, it provides invaluable insight to the UAM ecosystem on the concerns and studies that can be expected to be needed to satisfy local authority requirements as more operations are introduced in other markets.
For this specific opinion, the stakeholders are expected to submit their own feedback to the points raised by the Ae.
