Complex city environments need complex systems

This section outlines some of the high-level systemic requirements and challenges for long-term integration of drones into UK cities, in line with the findings of the Flying High project. The purpose of this document is to consolidate existing research and proposals for urban drone systems with learnings from the city engagement and the feasibility research conducted by Nesta. This document can be used to support strategic roadmapping, identify challenges and opportunities and inform policy for a national vision for drones.

Urban areas present particular challenges for aviation. Dense populations and infrastructure and a high rise environment increases the safety and environmental risk, as well as the impact of noise, light pollution and visual blight. For these reasons flights in cities at very low altitude are generally prohibited. With some exceptions, the Rules of the Air require aircraft in a city to fly at least 1000 feet above the tallest building within 600 metres. Small unmanned aircraft (drones) have a very different set of rules to other forms of aviation, but also have particular restrictions in cities.

Drones are operated in urban areas today, but in general this is either recreationally in wide open spaces like parks, or use by commercial operators with special permissions and exemptions from the Civil Aviation Authority (CAA). These exemptions are granted on a case by case basis. Drone use is governed by the Air Navigation Order (ANO) 2016. Unless an exemption is obtained from the CAA, drones fitted with cameras are not permitted to be flown within 150 metres of a congested or built up area (which includes all urban areas with exception of some wide open spaces) and all drones must be operated within visual line of sight of the operator, within 500 metres horizontally and below 400 feet in height, the latter becoming law in a May 2018 update to the ANO.

To gain exemption from these restrictions from the CAA it is necessary to produce a safety case outlining how the proposed drone deployment will be conducted safely. This safety case is contingent on the technology being used, the operator of this technology and the requirements of the mission such as location, duration and time of day.

The engagement with five UK cities conducted through the Flying High project has identified a wide range of application-specific and wider benefits that drones could bring to cities, summarised in the ‘What drones can do in UK cities’ section of this report. Many of these operations in the short term can be realised through the existing system of applying for a CAA exemption to operate in a congested area and sticking largely to the existing regulatory framework outlined in the drone code. But in the longer term, drone integration will entail going beyond the existing framework, allowing regular operations in currently restricted areas, with a level of autonomy, beyond the visual line of sight of an operator (BVLOS) and eventually without an operator at all.

This will mean integrating drone operations into the everyday running of the city. Drones will start to have a significant impact on the city and its operations, affecting the way government and firms are run and organised, the nature of the built environment, and the ‘feel’ of the city. New systems will need to be put in place to manage the use of drones and integrate them with ground-based systems and traditional aviation. Governance of these systems will need a combination of aviation and city management expertise, and involve city and national governments, airspace regulators and air navigation service providers. Developing these systems will be an evolutionary process building on the limited urban drone operations that exist today, rather than a sudden shift to mass deployment. It will also be a complex process, driven by a mix of factors that include public acceptance, social impact, economic viability, infrastructural and technological possibilities and regulatory frameworks.

This chapter explores some of the major systemic issues and challenges that need to be overcome for the future integration of drones into UK cities, drawing on learnings from the Flying High project’s city and wider stakeholder engagement, research into the feasibility of the five use cases and supplemental desk-based research. It considers airspace and air traffic management, infrastructure, governance and public acceptance.

Below: Top down view of how drones could operate in future cities

Existing initiatives

What is being developed around the world?

U-Space

The most significant drone integration programme currently underway in Europe is the U-Space initiative, part of the Single European Sky ATM Research (SESAR) joint undertaking. SESAR is a public-private partnership involving the European Commission, Eurocontrol and a number of air navigation service providers and industry stakeholders. These players have been developing the ‘U-Space’ concept; a set of digitally-driven services that will enable complex drone operations at scale, involving a high level of autonomy in complex (particularly urban) settings. These services will be part of a future Unmanned Aircraft System (UAS) traffic management (UTM) ‘system of systems’. A roadmap for developing these services was published in March 2018. The roadmap envisions a phased development and roll out of services which will enable increasingly complex operations, up to fully autonomous drone operations in 2035. It ultimately includes integrating drone traffic management with traditional manned aviation, so that drones and traditional aircraft can operate in the same airspace. Details of the project are available on the SESAR webpage.

NASA Unmanned Aircraft System Traffic Management

NASA is collaborating with the US Federal Aviation Authority on the development of traffic management systems for civilian drones to enable operations in low altitude airspace. The project takes a gradual capabilities approach, split into four sequential technological capability levels. Previous demonstrations have included enabling BVLOS flight in sparsely populated areas, managing drones with both cooperative and uncooperative traffic in moderately populated areas. A forthcoming stage will enable operations in densely populated (i.e. urban) areas and deal with large volumes of traffic. Details of the project are available on the NASA website.

European Aviation Safety Agency drone categories

The European Aviation Safety Agency (EASA) is in the process of drafting new regulations to cover non-state use of drones, and is taking a risk-based approach that splits drones into three main categories:

• Open: This is the lowest risk category, where certified drones would operate according to certain principles without the need to get authorisation from the authority for a given operation.
• Specific: A higher risk category requiring authorisation for the drone deployment/type of deployment. This means a risk assessment needs to take place, factoring in the capabilities of the drone, the operator, the environment and the specific task.
• Certified: The highest risk category where both the drone and the operator must be certified by a relevant authority.

The different use cases for drones could involve all three categories. Part of the challenge involves integrating the different drone risk profiles outlined here, for drones performing missions of different operational types.

Principles of urban drone integration

Ground-rules for how drone systems should be developed

The integration of drones into city ecosystems will ultimately depend on what is socially acceptable and technically possible, but also on the financial cases and business models. These will have a defining impact on how city drone operations - and the frameworks around them - evolve. Already there is a strong, validated business case for many types of drone operations in cities (notably for media, surveying and construction). Facilitating deployment, pushing the boundaries of what is technologically possible and what is allowed by current regulation will yield a range of new and unexpected benefits that could shape drone integration in unpredictable ways.

Some applications that will have a significant impact on cities (such as proactive infrastructure repair, logistics or passenger transport) are becoming increasingly possible, but have not yet proven their economic and social viability. The business models that emerge around these applications, should they prove plausible, will have a significant impact on the evolution of operational characteristics of urban drone use.

Although the system will evolve naturally, we believe that cities should have a role in shaping that evolution to meet the needs of citizens; to maximise the benefits and mitigate the downsides. Through our stakeholder engagement process we have identified six key considerations we believe must characterise the process of urban drone integration:

1. Safety.
2. Security.
3. Privacy.
4. Transparency.
5. Accountability.
6. Environmental protection (including noise, visual pollution, emissions).

Types of drone operation

Different drone applications operate in fundamentally different ways

When considering the challenges to drone integration in cities, a key factor is the characteristics of drone operation. Current drone use in cities is all of a similar type; piloted, within line of sight of the operator and usually on a one-off basis. The drone applications that have been highlighted by the Flying High project’s partner cities, however, are associated with quite different operational characteristics, technologies and regulatory requirements. We have outlined some of these different types of operation below.

These different types of operation could all exist alongside each other in the same urban airspace (in the same altitude range and parts of the city) and even alongside manned aviation, which is currently separate from drone operations due to the 400 foot height limitations. Alternatively, it could be that only certain types of drone operation are appropriate to a particular location or city, though this may limit the benefits drones could bring to that area.

• Piloted vs autonomous drones. Current legislation and standards are built around all drone flights involving a human, either directly flying the drone or monitoring a pre-programmed automatic flight. In the future it is very likely that drones will be able to complete missions with a high degree of autonomy. At a minimum they could conduct routine pre-programmed operations without the need for immediate supervision (highly automated), autonomously detecting and avoiding obstacles. In this scenario, drones would need to communicate automatically with other drones and with air traffic control, and make decisions about factors such as landing site or flight path (what the CAA refers to as ‘high authority automated systems’). Drones of different levels of autonomy and drones remotely piloted by a human may soon operate at the same time and in the same airspace.
• Type and capability of drone used. There is a diverse range of unmanned aerial vehicles, each with very different designs and capabilities; from fixed wing, to multirotor to hybrid, and a range of size, payload type and capability. City skies and management systems will need to accommodate very different types and capabilities of aerial vehicles operating at the same time, in the same airspace. It may be necessary to designate new classes of drone based on capability and autonomy, in addition to the existing classification based on weight and payload. New drone classifications could be subject to different rules and airspace access.
• Routine vs one-off deployment. Some drone deployments may require continuous deployment via tethered drones or drones that run the same route repeatedly (e.g. for routine deliveries, inspections or surveillance). Many other operations will be discrete, single deployments to carry out an individual task, for instance a search and rescue operation or to carry out a one-off site survey.
• Journey vs contained deployment. Drone deployment could involve a journey from one point to another (e.g. medical delivery between hospitals), while some deployments will necessarily be confined to a limited area (e.g. construction site monitoring), or may involve a tethered drone. The former is likely to involve BVLOS flight, and will have to operate alongside more traditional piloted, visual line of sight flight.
• Journey type. Multiple journey typologies may occur - fixed location to fixed location (A to B), fixed location to a variable location (A to X), or from a variable location to a variable location (X to X). A variable location could be one where the location is determined at the start of the operation (e.g. a delivery of a defibrillator to the scene of an incident) or where the end of the operation is unknown at the start (e.g. a police pursuit).
• Application type - civic vs commercial vs recreational. There is a range of potential drone operators in urban environments that would need to coexist. Drones being operated for commercial purposes may have to operate alongside drones being used for civic applications such as emergency response. There is also an active research and hobbyist community using drones who will want to access airspace.

Airspace

A major challenge of urban drone integration is how to manage the airspace and air traffic. Under the ANO 2016 it is prohibited to fly a drone (if fitted with a camera) within 150 metres of a ‘congested or built up area’, which includes the majority of urban areas, or higher than 400 feet in altitude, without permissions or exemptions from the CAA. However, if drones are to be deployed at a larger scale in UK cities there will be a need to streamline access to low altitude urban airspace for drones and to develop new ways to manage that airspace to ensure compliance with regulation, deconflict traffic and identify rogue operators. This would involve new rules for airspace management, new controlled zones or even new airspace classifications or redefining of existing classifications.

Because aircraft generally must operate at least 1000 feet above the highest obstacle within 600 metres in cities, low altitude airspace is unlikely to be heavily occupied at present (with the exception of certain low altitude flight routes, or in exceptional circumstances) Increased drone use could change that.

City stakeholders, including local government, should be involved in what happens in this airspace. They should be able to have some control or decision making power over what goes on in their airspace, should there be a move to increase its usage. Urban airspace could thus be conceived as a separate category from other types of airspace, not just in the sense that, as is the case at present, different rules apply, but also that the city authority would have a role in managing it.

The approach of airspace regulators such as EASA and the CAA is that airspace should not be segregated for particular users or uses, but considered as a national asset to be shared. Thus no one can ‘own’ the airspace and it can be accessed by all, excluding any temporary segregation for necessary safety or national security purposes, or for testing new technology.

This is the basis of the flexible use of airspace principle developed by Eurocontrol and adopted by the CAA, initially developed to integrate the traditionally separate military and civil airspace. The trajectory of organisations developing solutions for the integration of drones such as SESAR and NASA is to carry forward these principles of non-segregation and equal access to airspace as a shared resource. This implies that there will be no segregated airspace in which autonomous or remotely piloted drones operate exclusively, and no private airspace zones or lanes for exclusive use or rental by a single entity or group of entities.

Drones could, in theory, operate alongside helicopters and even commercial aircraft above and around cities, but they would need to meet certain requirements to operate in both controlled and uncontrolled airspace alongside traditional aviation. This includes being able to sense and avoid other airspace users and be able to fly accurately and follow air traffic control instructions within controlled airspace (if the drone is above 7 kilograms according to the ANO 2016).

No-fly and special permission zones

Areas where drone use should be heavily controlled

Low altitude airspace away from airports is generally uncontrolled by air traffic services and not widely used by manned aviation. However, should drone operations become commonplace in cities, then in order to maintain safety, privacy and environmental standards it would be necessary to have designated areas of controlled or restricted urban airspace.

These may be areas where drones are not allowed at all without special permission, ‘no fly zones’, or where only certain types of drone are allowed by default. Restricted areas already exist around airports, military bases, prisons and sensitive sites such as nuclear power stations. It may be necessary to designate additional areas as no-fly or special permission zones for low altitude flight, which may include large parts of cities. It may also be desirable to make the default permission for some currently restricted areas more nuanced, to allow for certain types of operation (such as by the emergency services).

Restricted areas would then be coded into positioning systems such as GPS, a process referred to as geofencing, with operators alerted if the drone trespasses into an unauthorised zone. Geofenced areas may be permanent or dynamic; a temporary no-fly zone could be set up in a particular location during an incident and a set of exclusionary GPS coordinates updated on the drone if, for example, emergency services need to respond to an incident using a drone. Drones (or their operators) with different capability levels could be granted access to different types of location, just as the ‘open’, ‘specific’ and ‘certified’ categories developed by EASA have different requirements, and are further divided into different classes of drone with different certification standards.

Another approach to restricting drone operations is to define specific areas within which a drone must operate These can also be coded into the drone with GPS or other location data, and the operator is alerted if the drone goes outside this zone. This is referred to as geocaging. This may be necessary to preserve privacy in a scenario where drones are able to operate largely autonomously and BVLOS, though current capabilities may not be robust enough to ensure compliance, as the system could be bypassed by a rogue operator.

Flight paths

Highways of the air

Regular BVLOS drone flights from A to B, such as those involved in delivery or passenger transport, may be best achieved by directing traffic along particular corridors. These would help to manage traffic when the volume of drones in the sky becomes high. They could also be used to mitigate any negative impacts on people on the ground by avoiding residential or sensitive areas. Flight lanes could be layered to enable drones to move in opposite directions or at different speeds along the same paths.

It may be preferable for flight paths to follow the existing landscape and infrastructure. Flight paths above rivers would reduce the risk of a crash to people and buildings, while following infrastructure such as highways, railways or power lines could reduce nuisance to people under the flight paths. Though here emergency landing sites would need to be identified and the risk to underlying infrastructure assessed.

Should drones become fully integrated with manned aviation it can be expected that remotely piloted or autonomous aerial systems would operate in the same space as helicopters, or even largely replace helicopters. As things stand, helicopters have to fly high enough that they can safely autorotate (glide) away from a built up area in the case of engine failure, and in some places (such as London) that means following particular corridors.

Passenger drones may not follow traditional helicopter design (many are multirotor or vertical take-off and land fixed-wing). Should these become viable there will likely need to be a new regulatory framework, for example including a minimum level of redundancy. However, there may still be an argument for these aircraft following current flight paths as far as possible for safety and to limit noise pollution.

It is also worth noting that while this would not necessarily require segregation of the airspace for drones - in theory anyone could access the low altitude flight paths - it does mean a new approach to controlling that airspace.

UAS traffic management

Developing a drone traffic control

Should low altitude airspace in cities be opened up, including to autonomous systems, it will be necessary to have the infrastructure in place to manage that airspace.

Existing air traffic management systems are based on visual information, communication with a pilot and on the pilot’s ability to take action. As usage of unmanned aircraft expands, and if rules around line of sight and presence of an operator are relaxed, new processes will need to be developed to manage increasingly complex and high-volume traffic.

One solution could be to restrict operations to certain capabilities or parameters or by segregating airspace, but current trends are towards the development of a UTM system. A core function of this will be logging, managing and informing different operators of what is in the air.

Drone flights would be logged in a UTM system either before or during the flight. The system would then inform the operator of existing traffic and could manage the flight parameters with dynamic data on obstacles, the weather, and possibly (dynamically) geofenced locations. This system will need to be heavily automated to be efficient. It would need to accommodate both piloted and autonomous systems as well as manned aviation and non-cooperative traffic such as birds or rogue drones.

Another important aspect of the UTM would be how it integrates with air traffic control (ATC). At a minimum, drone flights should be visible to air traffic control to mitigate risk. Should drones operate in the same airspace as manned aviation, alongside helicopters or even around airports, the UTM will need to communicate with ATC or even function as a single unified air traffic management system for both manned and unmanned systems. As well as integrating with ATC, different types of unmanned systems could also be managed by a single UTM, including connected and autonomous vehicles and autonomous marine vehicles.

Many UTM services already exist in some form, particularly for flight logging and tracking, and more are in development by both the private and public sector. Many different management systems may need to operate concurrently, much as different air traffic management solutions are used today by different airports and air navigation service providers. Different UTM systems will need to be interoperable to communicate with each other, with diverse types of drones, and quite likely with air traffic control for manned aviation.

If diverse UTMs for different drone fleets or different components of UTM are developed separately, they will all have to either be standardised, regulated and completely interoperable with each other or be interoperable with a centralised system of systems. This could be run by the air navigation service provider (such as NATS) or an entirely new entity. Efforts are ongoing at the international level to coordinate and harmonise UTM development, notably involving NASA, the SESAR’s U-Space initiative, the Japanese Ministry of Economy Trade and Industry, and the Global UTM Association.

The UTM system can be split into technologies that will need to be built into the drones themselves (though some already is), applications and software for managing drone traffic, and infrastructural requirements such as communications and positioning systems.

The Global UTM Association has identified the following components of a UTM system in its April 2017 report ‘UAS traffic management architecture’:

• Identification: UAS and operator/UAS pilot identification capabilities, to be able to identify UAS pilots/operators and UAS flown in a UTM-monitored airspace.
• Flight plan (operation) management: Flight plan/operation data management and authorisation capabilities, to collect (providing common human machine interface for UAS pilot or operator or by interfacing/interoperating with the UAS service supplier system), analyse and validate UAS operations.
• Flight permissions and directives: Flight permissions and directives, issued or denied manually or automatically based on data such as airspace restrictions, weather conditions, obstacles, other aircraft, and registration data.
• Airspace management: Airspace management capability, to act as the single point for adding or removing any permanent or temporary airspace restrictions (referred to as geofencing at the UAS level).
• UAS surveillance and tracking capabilities: to provide situational awareness.
• Conformance monitoring: Conformance monitoring capability, to check the compliance of flight progress in respect of the declared plans.
• Meteorological information: to inform on local weather information regarding the operation.
• Obstacle information: to inform on obstacles related to the operation.
• Conflict detection and advisory capability: to anticipate the risk of collision between UAS and manned aircraft, and of entering restricted airspace.
• Contingency management: To inform in the event of emergency situations.
• Recording and playback capabilities: to provide evidence during post-flight phases (e.g. incident investigation, statistics).

Further to these, there will need to be capabilities on the drone itself, including:

• Navigation and piloting capabilities, which are essential to the conduct of safe operations.
• Geofencing (or geo-limitation) capability support, to respect constraints imposed (stay-in and stay-out volumes).
• Identification capability, to ensure cooperative surveillance.
• Detect and avoid capabilities for obstacles.
• Termination and return-home capabilities for reducing the risk in case of contingencies.
• Operation planning, to support the UAS pilot or UAS operator in defining the operation.
• Monitoring and control support, to follow in-flight UAS operations.

Many of these systems are already in place. The challenge is in unifying them, having them interact with autonomous systems and dealing with traditional aviation and non-cooperative traffic.

Capability-driven approach

Permissions for drones need to be linked to what they are capable of

Development of an urban UTM system is envisioned by key players in Europe and America (SESAR, NASA and the Federal Aviation Administration) to be evolutionary and to involve multiple stakeholders working on different component solutions that would feed into a UTM system of systems. UTM component developments have been largely led by industry to date, but collaboration with governments and regulators will be key.As the system evolves it will need to accommodate drones with differing levels of capability. It will have to provide particular services that require particular capabilities and infrastructure to be in place, even though there may be minimum requirements for drones to operate at all. For example, some form of digital signal broadcast to tracking systems, known as electronic conspicuity, would be required. This capabilities-driven approach would involve:

1. Defined levels of capability required of the drone system. These would have to access...
2. Defined capability levels of service of the UTM, in particular types of environment that have…
3. Defined capability levels of infrastructure.

For example, only drones that broadcast their location, have certified navigation capability with sense and avoid technology could operate above 400 feet in an area of over 90 per cent mobile coverage.This capability-driven approach will allow advanced applications to be tested and deployed while still accommodating legacy drone systems. EASA are evolving regulation alongside product standards for drones, that will be split into different classes for different drone capabilities, effectively endorsing the capabilities approach.

Communications and data infrastructure

Safe operation of drones needs reliable communications networks

For drones to be integrated into airspace, they will need to communicate with the air traffic management system and with other drones. Depending on the application, drones might use different communication methods including mobile phone networks, satellite, and other radio communication.

Mobile phone networks are a promising way to handle communications because the infrastructure already exists, and can be used for control and monitoring of BVLOS operation. Mobile networks are also fast and secure.

There is normally good mobile coverage in urban areas, however these networks are optimised for use on the ground. Their coverage is not necessarily as good in the air. In cities there are also often issues around bandwidth due to the high volume of users. Using mobile phone networks also benefits from upgrades to the mobile infrastructure, such as the upcoming 5G capability which will greatly improve speed, latency and capacity. Since the mobile phone system already has the ability to identify cell phones through SIM cards, this capability could be used to identify drones. Mobile phone towers could also be used to help drones find their location by triangulating between several towers.

Although satellite communication is unlikely to be used as a primary method to communicate with drones in most circumstances (where mobile data networks are cheap, reliable and secure), drones will still likely make use of global navigation satellite systems such as GPS and Galileo. To improve accuracy, drones may also use the European Geostationary Navigation Overlay Service, which improves the accuracy of satellite navigation systems.

For applications where there is an existing radio network, that could be used too. For example, emergency services drones might connect to the emergency services network which is currently under development.

For all of these communications methods it will be important to map out the signal strength in the places the drones will travel. For mobile networks, it’s unclear how well they’ll be able to be used for communication because they are optimised for ground use. Also, buildings in cities can interfere with signals such as GPS.

Drones will also need to communicate with each other for sense and avoid capabilities. These may be similar to the current sense and avoid systems on aircraft such as FLARM, which broadcasts location data and monitor/sense for nearby aircraft. Some off the shelf drones come with basic sense and avoid ability. However, this is limited and mostly focused on sensing and avoiding obstacles in close proximity to the drone, rather than airborne collision avoidance, which is a more complex challenge.

The illustration below summarises how urban airspace might be managed in the future, illustrating a distinct, low altitude ‘urban airspace’ where drones could operate and where the city would have some jurisdiction.

Changes to the built environment

The proliferation of drone technology, if it occurs on the scale described in this report, would have an evolutionary effect on the built environment, and on the very nature of our cities. Certain drone applications or types of operation could result in the need for new physical infrastructure. If systems become highly automated they will require fixed docking stations to take off and land from. This would give them designated take off and landing points, which could be integrated with charging or refuelling capability.

Several companies are currently offering or developing different types of docking station, often combined with charging capabilities, or automated battery swapping. A high level of deployment, routine automated flights or particular applications such as delivery will increase the need for docking stations. This could be a temporary/mobile or permanent fixture, which may be placed on the top of buildings, at ground level, integrated into existing transport infrastructure or on other types of infrastructure such as lampposts. It is likely that these docking stations will be integrated with battery charging; how this may affect the grid and associated emissions will need to be considered, as demand for electricity increases with the growth of electric road vehicles.

Drone systems could affect the way buildings themselves are constructed. For example if drone delivery hubs are on the roof there will need to be a way to easily access the rooftop or to transport goods to and from it. New buildings could be designed to accommodate this, but it could be a serious challenge retrofitting old buildings. The visual impact on the built environment would also need to be considered.

Passenger terminals and logistics hubs

Other potential changes to the built environment include terminals for personal transport or hub stations for logistics. Many remotely piloted or autonomous aerial systems for personal mobility are currently being tested or are under development. These could end up being deployed at scale as flying taxis, or simply be a cheaper, autonomous electric alternative to helicopters. So far the viability of this technology, and particularly the business case around mass deployment, has not been proven. However zero emissions and autonomous passenger aviation technology in cities can be expected to evolve and eventually may lead to entirely new operating models. Where small electric air mobility solutions are deployed in some form in cities, these would need terminal infrastructure around them.

Package delivery of some kind has been identified as an application of interest by the Flying High partner cities. Even if this is limited to urgent items or medical items, a built environment solution will be needed to send and receive goods. This could either work as a local hub model, point to point or from a hub to an unknown location.

Counter drone systems

A key part of an air traffic management system for drones will be understanding what it is in the sky at any one time. This will involve a UTM having access to operator registration information, and flights logged by operators. Drones may have a mandatory electronic conspicuity device such as a transponder or the ADS-B (Automatic Dependent Surveillance - Broadcast) technology currently used by commercial aviation. This will enable identification of cooperative traffic, but should increasingly advanced drone technology continue to become readily accessible, there may need to be ways to identify and respond to non-cooperative air traffic.

A raft of solutions are being developed for this, which include jamming the radio frequencies to block remote control of a drone, and even means to safely take drones out of the sky, for example using nets with parachutes.

One approach would be to have ground-based systems to detect rogue drones around particular sites, and counter-drone mechanisms to deal with them. This may mean fixed infrastructure such as radar, signal jammers and drone capture technology placed on or near certain sensitive sites such as prisons or government buildings. Alternatively this could be a capacity that sits with the police, to be deployed as needed. The solution will depend on the capability and availability of potentially harmful drone technology, and if drones operated with malicious intent are able to blend into a future where seeing a drone in the sky is an everyday occurrence.

Regulatory frameworks

The existing national regulatory framework around drones is set by the Department for Transport (DfT), and regulated by the CAA. There are international efforts to coordinate new policy frameworks and standards for drones, brought together by the Joint Authorities for Rulemaking on Unmanned Systems. Policy relating to drones will be a mixture of policies and standards at the international, national and local level. Local government in cities should have flexibility with respect to drone operations, within a larger national and international framework.

The operational rules covering drones in the UK have a set of default restrictions and ad hoc exemptions that are appropriate for the current level of technological capabilities. The huge increase in drone use in recent years has put pressure on the regulator to deal with an increasingly large volume of applications for permission and exemption. In the future, operations that would currently require exception from the CAA may well become routine, including operating in dense areas and BVLOS. Future operations are also likely to involve a high degree of automation, both of the drones themselves and the traffic management system.

EASA is currently developing new regulation for drones, based around different categories of risk (open, specific, certified), and it is plausible that the UK will adopt this framework. It includes registration of drones that pose certain risks (e.g. are able to transfer 80 joules of terminal kinetic energy), or are in the certified category. It will also facilitate the permissioning of operations beyond the standard restrictions (including BVLOS) through the use of standard scenarios associated with particular drone capabilities and operator requirements. These standard scenarios will need to evolve to take into account autonomous systems and urban operations.

As the technological possibilities increase and safety, security and privacy challenges are able to be mitigated, a new default set of rules governing urban skies will be needed. A range of standards will be required for a UTM system of systems to operate. Standards around this are likely to be needed for drone capabilities such as engine type, power source, redundancy, electronic conspicuity, communications and failsafe protocol. Additionally standards will be needed for how the UTM manages traffic, for instance how flights are logged and permissions is granted or denied, how volume of traffic is or isn’t restricted and possibly how the system communicates and receives information from air traffic control.

Management of urban drone use

Controlled airspace has traditionally been administered by air navigation service providers; this is typically a government entity though NATS in the UK is a joint venture between the government and private sector shareholders (primarily airlines).

The management of drones in cities presents an entirely new challenge for aerial traffic management. This includes how it relates to aircraft, altitudes and distances that are very different from those currently managed by air traffic control, as well as dense populations and associated safety and privacy risks. A UAS traffic management system will thus be quite distinct from traditional air traffic management, even if some of the principles will be maintained.

The UTM will most likely need to integrate with traditional air traffic control if airspace is not to be segregated for use by drones. It is likely that many different UTMs will be developed and operated by different players at the same time, but these components will need to be interoperable and be part of a system of systems accountable to the state in some form. The system of systems could be a set of interoperable solutions governed by state-set standards, or it could a piece of digital infrastructure itself, managed by or on behalf of the state.

As low altitude airspace directly impacts on the city environment, cities should have a voice in how this airspace is managed. Indeed, low altitude drone traffic management services could be run by, or on behalf of, the local authority. Cities could pick solutions from a set of state-standardised services offered by sanctioned providers, just as air traffic control services are procured locally.

Drone traffic management services may also involve traditional aviation service providers such as NATS, or an entirely new private or public body created to manage low altitude drone traffic. At a minimum the city authority needs to have a strong voice in the management of its low altitude airspace. The best way to achieve this may be for the city to run or be responsible for procurement and oversight of these services.

Similarly local low altitude rules of the air should be set by cities within a national framework. This could be analogous to the highways department as a local authority, where specific rules are set with an overarching national framework. Cities could set rules around low altitude flight paths and restricted areas. Noise levels are already managed at a local level, but local authorities would have to take drones into account and factor noise into local drone traffic rules.

The business model for the operation of the UTM and how it will be paid for will also need to be determined. This could be delivered as a national service funded out of general taxation, but that would depend on being able to justify the use of public money through measurable social benefit or economic growth. Another option would be a pay to play system where users of the airspace must pay for UTM services either on point of delivery or as a subscription. This could be a public model like a road tax or toll for the sky, or a private model where users pay a privately owned operator for services.

Environmental impact

Increased drone use could have an adverse environmental impact and this will need to be assessed when considering higher levels of deployment, particularly the impact on noise, visual and light pollution, climate change and air quality, effect on wildlife and life cycle of the drone technology.

Noise from aviation can be a major nuisance, the extent of which is related to the type of noise, intensity and the relative background. Currently there is no legal limit on the level of noise permitted from a drone, indeed there is no legal environmental limit for noise from aviation. There are noise limits for occupational exposure and aircraft technical standards to limit noise, as well as noise being taken into account for planning applications around airports and for airspace classification.

Individual cities may also have particular policies on aviation noise. The CAA has a role of monitoring aviation noise and collaborating on and reviewing research into its effects and how they can be reduced. A recent study by NASA found that drone noise was more annoying than that of road vehicles, possibly attributable to greater familiarity with the latter. Legislation proposed by EASA includes restrictions on the noise permissible by drones of different classes.

Although drones are much quieter than helicopters, they also operate closer to the ground and may be used in larger numbers. Noise caused by drones will be a factor in any policy decision related to the increased uptake of drones. One approach to this would be technical noise-limitation standards in the UK.

People may dislike the sight of large numbers of drones and at night time low flying drones could contribute to light pollution. This will be a factor is considering and managing deployment levels in urban spaces and, in addition to noise considerations (which are often context dependent), may lead to operating hours and geographical restrictions on some types of drone operation. This could mean drones are not allowed to operate in particular areas at particular times.

Other environmental issues include the increased emissions from power stations resulting from large scale use of drones, the possible contribution to e-waste caused by difficulty of recycling drone technology and the impact increased drone deployment could have on wildlife, particularly disruption to birds. This will all need to be considered as drone use increases and an appropriate policy response formulated, if necessary.

Public acceptance

In addition to technical and regulatory barriers to developing an urban drone system, public acceptance will be key if drones are to integrate into city life. This will be necessary both in creating demand for drone services and for people to be comfortable enough living around drones for them to operate.

A recent DfT study on public perception of drones showed that awareness of drone technology and regulation is low and people tend to have a negative opinion of drones. The same study, reflected in other similar investigations, found that greater acceptance of drone technology is contingent on a number of factors, notably familiarity with the technology, the operator and application, and if the technology is delivering a personal or societal benefit.

The engagement with the Flying High project’s partner cities found that public dialogue and accountability are vital for any future integration of drones into city skies. Consultation on local drone policy and mechanisms by which people are able to input to policy and system design will be critical. Alongside this it is important that the public has an understanding of existing rules. Previous surveys, such as that carried out by the Royal Aeronautical Society in the UK, show that people by and large do not understand the current framework.

Demonstrations of the technology is one very powerful way to engage the public, in addition to a campaign of workshops, focus groups and online consultations. The DfT’s recent public dialogue on drone use is a good example of previous public engagement around drone technology that was in depth and sustained over time, providing an interesting snapshot of opinion across the UK.

Openness

In addition to procedural transparency, another tool that can engage citizens and drive acceptance is open data. One way to use open data would be by having publicly accessible aspects of a UTM system. This can help people stay informed and to better understand how drones are operating in their city. This could mean being able to log on to a site or use an app to identify the operator of a drone flying in the vicinity of your property, what type of data it is collecting, or even use an app to identify it via a mobile phone. It could also mean being able to log on and see all of the local drone operations that are ongoing in your area.

It would also be desirable to make the data collected by drones open where possible, and compatible with multiple public agencies. For example, where drones are being used to monitor traffic congestion, or capture aerial photography for city planning. This could have the effect not only of engaging the public, but also encouraging the development of new products and services based on drone data. These new products would themselves further normalise the productive use of drones.

Distributional impact and inclusivity

Many drone uses could have a negative impact on inequality, affecting different sections of society in different ways. It will be important that the system evolves in such a way as to avoid this and promote inclusivity. Uneven impact could relate to inequalities in access to drone services, to disproportionate effect on certain types of jobs, or on particular communities.

Certain applications and system design characteristics are more likely than others to create inequalities or negatively affect certain groups. For example, the use of drone mobility and delivery is likely - at least initially - to be a premium service only accessible to the wealthy. Should operating models involve fixed take-off and landing points there may be noise issues for people in the vicinity of these. To promote equitable development, these issues will need to be considered and steps taken to ensure that technology deployment is inclusive.