Peter Powell
By Peter Powell

Peter Powell has 15 years’ experience in understanding and managing the legal and commercial aspects of aviation infrastructure development. He has done this for three airlines and one eVTOL manufacturer.

opinions

Do eVTOL air taxis have a place in sustainable cities? Not necessarily

The countdown to the launch of eVTOL air taxi services is most definitely “on.” Perhaps you live in one of the cities that has already been told that air taxis “are coming soon to your neighborhood.” You’ll be glad to hear that regulators including the European Union Aviation Safety Agency (EASA) and Federal Aviation Administration (FAA) are actively engaging with eVTOL manufacturers to ensure that the relevant standards, regulations, and expectations are in place if and when they do.

Uber vertiport
Large, unobstructed vertiports such as this concept design for Uber may be practical in some cities, but not in others without considerable negative impacts and opportunity costs, the author argues. Uber Image

This is all great stuff. But now is also the right time to be asking more pointed questions of the industry. We need to consider what we know about air taxi operations — especially what we have learned over the last year or two — and evaluate their possible contribution to the concept of sustainable cities. This is the type of city I want to live in, and I’m sure you feel the same way.

You may be thinking, “What could we possibly have learned about air taxi operations, when they haven’t even launched yet?” As it happens, quite a bit, as I’ll explain below. But first, let me make it clear that I am not advocating against air taxi services generally. Rather, I am sharing my view that air taxis in their current form are not automatically suited to all cities, just because they might be appropriate for one particular city. And this is something that urban planners and city officials should consider carefully.

We can start by agreeing that eVTOL air taxis have valid “green” credentials, at least to the extent that there are no greenhouse gas emissions from the vehicles. How the electricity which powers the vehicles is produced (coal, nuclear, solar, wind) is entirely dependent on the location of the operations. So, too, is the ability of that local grid to support the power requirements of multiple vertiports. So put this on your list, urban planners: Can your electricity grid handle the loads that will be demanded by air taxi charging systems?

But there is much more to consider when assessing if air taxis are right for your city.  As someone recently tasked with bringing together the technical, operational, and commercial requirements for vertiport infrastructure, I can tell you that there is a lot of relevant information already available to interested parties — it just needs to be put together in the right context.

Vertiports are essentially airports for VTOL aircraft. There are many different design proposals out there, but they all deal with exactly the same constraints related to aircraft type and physical infrastructure dimensions. For our purposes, there are three basic constraints that all vertiports will share. These include, firstly, utilization rates of the final approach and take-off area (FATO) due to airspace and vertiport configuration. Secondly, time constraints relating to passenger processing. And thirdly, the enormous technical challenge of battery charging times.

As you may already know, Uber’s Elevate white paper presents a very optimistic scenario about vertiport throughput performance in its infrastructure simulation. But I believe these assumptions are unrealistic, at least without a number of infrastructure elements that would be undesirable for most cities. Let’s start with FATO utilization.

A vertiport with one FATO will not be able to capitalize on even the most minimal aircraft separation rules (say, around one minute between take-offs and landings) unless it also provides a significant number of parking bays for aircraft and is situated in airspace with minimal restrictions to access. “Minimal restrictions” means, in this context, that there are no buildings or other obstructions on three or even only two sides of the FATO. Otherwise, approaches and take-offs run the risk of delays.

Numerous parking bays are required because eVTOL aircraft will need a place to recharge for 20 to 40 minutes once their batteries are substantially discharged. Moreover, the enplaning/deplaning of passengers will need to occur away from the FATO so that other aircraft may use it, and operations will require enough time to taxi the aircraft and then execute the appropriate customer service level in getting people and their luggage on and off the aircraft. 

But getting even remotely close to the turnaround time of five minutes put forward by Uber will also mean that the vertiport is configured in such a way that the parking bays are very close to the FATO (minimizing taxi time) and that the taxiways are not shared (to avoid traffic jams). Such a vertiport would need to be truly huge to conform to our assumptions, while also being located in a wide open space with no airspace restrictions.

Even if the model were amended to include multiple FATOs, you are still looking at a massive infrastructure footprint. FATOs under FAA regulations currently need to be 200 feet (60 meters) apart. Unless eVTOL aircraft can do away with the ground effect of their propulsion systems, there is little incentive, I would argue, to change this.

So urban planners and city officials need to think about the size of the infrastructure footprint for a vertiport to make any net contribution to urban mobility. To put this in further context, let’s assume that the Uber Elevate model is achievable, and the vertiport can support 48 departures per hour. This would mean that a four-seater air taxi service operating from that vertiport will move 192 people from point A to point B in one hour. Not many. And again, this is based on some very favorable (unlikely?) assumptions.

So, I suggest that urban planners and city officials need to critically assess whether the air taxi investment is worthwhile for their city, at least in the short term when the relevant technologies are weak and unproven. In other words, what price does a city pay for having a low-volume mobility alternative, in terms of the opportunity cost of valuable urban land at least, and at a time when there is a recognized urgency to implementing significant greenhouse gas reductions at the very earliest opportunity?

The problems don’t stop there

As I noted, we already have a set of established rules which are guiding vertiport design at the tarmac level. It is obviously a good thing that eVTOLs can leverage experience, regulations, and guidelines from helicopters. These are the rules which dictate FATO dimensions, line marking configurations, lighting, parking bay sizes, etc. — and these are all based on the size of the aircraft.

VoloPort prototype
Skyports and Volocopter exhibited this prototype “VoloPort” in Singapore last year. Given the diversity of current eVTOL designs, cities that invest heavily in air taxi infrastructure now risk inadvertently creating monopolies for certain operators, the author warns. Volocopter Photo

Currently, however, there are well over 200 eVTOL air taxi designs, each of them unique and driven by a number of technical, economic, commercial, and social factors. For the time being, there is no compulsion on the designers to create aircraft within a certain size and configuration that would lend itself to standardization of vertiports.

Why do you care, as an urban planner? Well, because the moment you allow one air taxi operator to configure a vertiport for its own air taxis, there is the very real risk that you have created a monopoly for that first operator. You may find that other air taxis cannot legally utilize those vertiports due to the size and/or configuration of the second aircraft. Or perhaps you find that the battery charging system is not compatible with that which is already in place. Ouch! And this is before considering the different branding and business models of the air taxi operators — which will impact such things as “terminal” design and customer processing models.

But there is another conundrum on the horizon for any single operator, and therefore for any city that allows air taxis; namely, aircraft development. Specifically, what happens when air taxi technology allows for larger vehicles that would actually make a significant contribution to overall mobility? Reconfiguring a vertiport that is optimized for small vehicles would be an expensive proposition — and might not even be possible. There is a risk that the city would be stuck with outmoded, low-volume air taxis while larger, more efficient ones have to operate from another, presumably sub-optimal, location. I believe these are possibilities that urban planners and city officials should be thinking about now.

Another important aspect is the fact that air taxi operators and/or their partners will gradually accrue a large portfolio of city properties — leases and freeholds — comprised of these vertiports. These portfolios will be highly valuable in years to come, potentially further incentivising operators to act in ways that may not serve the local community. How does any single city or region obtain its fair share of that value and protect its own interests? Again, now is the time for urban planners and city officials to consider this — not after leases and construction contracts are signed.

Infrastructure-related issues aren’t the only ones that should give urban planners pause. There are also concerns related to noise, fire safety, flight altitudes, passenger security screening, and more — all of which can be anticipated based on what we know now. By preparing early, with the right information, urban planners can create and maintain sustainable cities while also helping the air taxi industry define the operating landscape. This could eventually save millions, if not billions, in potential sunk costs and/or monopoly rents caused by multiple technology platforms, airframe designs, and business models.

We all get it: The idea of urban air mobility is attractive because it gets vehicles off the ground, where we already have lots of congested transport systems. And flying is fun. But the reality at this early stage of technological development is that air taxis are at best an alternative form of transport only. And importantly, air taxi operations carry the risk of considerable opportunity, environmental, social, and financial costs for local communities.

To my mind, air taxis today represent a natural commercial exploitation of technological innovation — not an invention driven by necessity. Urban planners and city officials should bear in mind that just because you can do something, doesn’t necessarily mean you should.

Editor’s Note: If you would like to submit an opinion piece for eVTOL.com, please contact [email protected]

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