Andy Sage, director of safety transformation at NATS discusses how the UK's airspace will accommodate eVTOL aircraft in the future

Often from OEMs there is lots of hype about the innovative features, and benefits of new types of aircraft.

ANSPs such as the UK's NATS have a different role. They must facilitate the safe introduction of new types of aircraft being developed, solving challenges in partnership with industry and government.

As director of safety transformation at NATS, Andy Sage's phlegmatic attitude reflects that pragmatism. His role is to ensure that new and different types of aircraft are integrated into the UK's airspace safely. Around two thirds of his time now is spent working with eVTOL companies, who are keen to ensure they have access to the UK's airspace in the future.

While there are hundreds of eVTOL aircraft in development around the world, the leading developers are approaching final certification testing, training pilots and beginning to consider infrastructure. Investments into eVTOL aircraft are huge and analysts predict the market will be worth up to US$1.75 billion before the end of the decade. But as Sage points out “unless eVTOL aircraft can fly where they want in the way they want, that bit of paper from CAA and EASA won't be worth very much.”

“In the last 18 months manufacturers have begun to understand the role that airspace has in the ecosystem and are looking to us to help them work out a roadmap for scaling up operations,” he says.

NATS is working to a timescale that predicts the first eVTOL aircraft will be certified in two years. There is high demand to access the UK's airspace from eVTOL aircraft developers.

“Fundamentally NATS has a duty to safely and efficiently accommodate any user who has a legitimate demand on our airspace. It doesn't matter whether it is an eVTOL aircraft, BVLOS delivery drone, helicopter operator or a high-altitude persistent drone. They all have their challenges and are all knocking on our door.

“But we do not want to disrupt current users or negatively impact efforts to reduce carbon footprints.”

London project

Sage was involved in a two year project to produce a concept of operations (ConOps) for Urban Air Mobility (UAM) in London which which published its findings in March. An industry-wide effort to envision how eVTOLs can be introduced into UK airspace, it involved eVTOL developers Embraer's Eve, Vertical Aerospace and Volocopter, as well as NATS, Heathrow Airport, London City Airport, Skyports and Atech.

London with eVTOL
Artist's impression of an eVTOL air corridor in Central London (Image: Eve Air Mobilty)

The London UAM ConOps delivers a regulatory roadmap to the UK regulator, the Civil Aviation Authority and a pragmatic view of the market. “It moves industry on significantly about how it can scale up operations over time,” says Sage.

The central use case proposes eVTOL aircraft flights running in a corridor between London Heathrow Airport in the west of London and London City Airport in the east, with stop offs along the way. London was picked because of the large amount of existing air traffic, including helicopters.

NATS conducted simulations for the project that considered how the demands and requirements of the route would be met using current airspace procedures and technologies. It then assessed when the route would hit capacity and new procedures and technologies needed. This simulation work helped to define the roadmap for a phased technology introduction.

The London ConOps and regulatory roadmap, which can be downloaded and viewed now, has been well received by the industry, with positive feedback from manufacturers and other ANSPs. “People see it as ambitious but pragmatic – based on a realistic understanding of how the business works,” says Sage. “The ConOps determines that VFR [visual flight rules] and the current regulatory framework are good enough to get the eVTOL industry started, but that it has limitations. You won't be able to fly everywhere you want on demand to start with – it may be a more scheduled service,” he says.


For the purposes of the project NATS viewed eVTOL aircraft as alternatively powered helicopters. But key differences were considered.

With limited battery capacity at least initially it is expected that eVTOL aircraft will be unable to hover and wait for access to vertiports. Another difference is their higher speed compared to helicopters. eVTOL aircraft will need to know a landing slot is available when they depart. This type of flexibility can be provided using current methods, but only up to a certain point. “It doesn't take that much in terms of demand for procedures to be tested,” says Sage. “At that point we will need to use some of the techniques from commercial aviation for capacity management. Digital towers will also play a part for smaller airfields that want to become transport hubs.

“If you look at the number of forward orders of eVTOL aircraft and the small number of markets initially being targeted, it is easy to imagine that within three to five years further solutions will need to be developed. But only if the demand and appetite is there from industry.

“Ultimately if industry appetite is to fly where they want, when they want, on demand you must change the way the airspace is managed and structured. It will require a high level of integration and not dedicated corridors.

“To achieve that level of integration requires airspace managers such as NATS to evolve the service it provides. If you don't, you will see a greater segregation in the market which won't provide what the industry wants.”

If the key to accommodating eVTOL and other new types of aircraft is airspace integration, unmanned traffic management (UTM) technologies and procedures will be needed. Sage says, “There has to be a convergence between ATM and UTM, a greater level of digitization and automation of the services we provide both inside and outside controlled airspace.”

There are fundamental building blocks required to manage airspace in an integrated way, believes Sage. Every aircraft must be conspicuous to each airspace user. International standards are also required to ensure that safety cases meet the needs of the market and users.

First routes

That the corridor considered by the London ConOps simulation stretched from one airport to another hints to where the first eVTOL aircraft will operate. The first routes will be decided by operators, but assumptions can be made.

“Inevitably people will look to airports first because you get the footfall and connectivity needed in these places already. That is why airlines are making large forward orders of eVTOL aircraft – they want to diversify and expand,” says Sage. “But some of the more interesting use cases are linking connectivity points which are under-served by current modes of transport.”

london eVTOL air corridor
Artist's impression of eVTOL air corridor in London

One of the challenges to introducing eVTOL aircraft is trialing integration while maintaining uninterrupted access to the airspace for current users. Some countries with larger areas of airspace available than the UK have created dedicated areas to test vehicles. “But the results of these trials don't necessarily carry across to working airspace,” says Sage. “Our approach is that you only start to learn when you start flying in the environment you want to fly in with the customer.”

Dealing with variety

As well as preparing for the advent of eVTOL aircraft, NATS has been supporting BVLOS (beyond visual line of sight) drone trials in the North Sea for several years to oil and gas installations, primarily for monitoring methane emissions. The ANSP has also been working with an operator in the North Sea to integrate unmanned BVLOS drone operations alongside helicopters in unsegregated airspace.

The ANSP is also working with several companies trialing point-to-point drone operations for logistics in temporary segregated airspaces. But is not working on projects that trial small delivery drones in urban areas. “We are just not seeing the demand for that in the UK,” says Sage.

Access to space using the UK's airspace is another change coming soon. Small satellite launch company Virgin Orbit is planning its first launch from Cornwall, England later this year. SaxaVord spaceport in the Shetland Isles, Scotland also hopes to host the first UK space launch ever before the end of this year. “Operationally we are already working on accommodating this and are looking at it in a planned and holistic way,” says Sage.

The future then holds the promise of not just an increased number of traditional and eVTOL aircraft, but several different types of air vehicles and operations. There will be variance in different markets, but eventually standardization will happen, Sage believes.

“There are signs that industry is working collaboratively to generate a shared vision, albeit under the auspices of the UK Government setting the direction in terms of airspace modernization,” says Sage. “NATS has a unique position to provide a leadership role in this space. We can be independent and are best placed to assess how proposals impact existing users.

“We have led many innovations, but those have all been evolutionary steps within the established market structure – airports, airlines, ANSPs. This is a fundamental change to the entire market construct.

“The extent to which it happens is the real question and opportunity – the innovation needed for these lower carbon forms of transport will carry over to larger aircraft one day.”