Release of Sterile Mosquitoes with Drones in Urban and Rural Environments under the European Drone Regulation

  Citation: Garcia, M.; Maza, I.; Ollero, A.; Gutierrez, D.; Aguirre, I.; Viguria, A. Release of Sterile Mosquitoes with Drones in Urban and Rural Environments under the European Drone Regulation. Appl. Sci. 2022,12, 1250. https://doi.org/10.3390/app 12031250 Academic Editor: Augusto Ferrante Received: 6 December 2021 Accepted: 14 January 2022 Published: 25 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). applied sciences Article Release of Sterile Mosquitoes with Drones in Urban and Rural Environments under the European Drone Regulation Manuel Garcia 1, Ivan Maza 1,* , Anibal Ollero 1, Daniel Gutierrez 2, Idoia Aguirre 3and Antidio Viguria 4 1GRVC Robotics Laboratory, University of Seville, Avda. de los Descubrimientos, s/n, 41092 Seville, Spain; manuel.garcia.river[email protected] (M.G.); [email protected] (A.O.) 2Instituto Tecnológico de Galicia, c/Cantón Grande 9, Planta 3, 15003 La Coruña, Spain; dgutierr[email protected] 3Centro Tecnológico de Automoción y Mecatrónica, c/Cantón Grande 9, Planta 3, Plaza Cein 4, 31110 Noain, Spain; [email protected] 4Advanced Center for Aerospace Technologies, c/Wilbur y Orville Wright 19, La Rinconada, 41300 Seville, Spain; [email protected] *Correspondence: [email protected] Featured Application: Drones can be a very useful tool to help mosquito control tasks in areas where these insects are an important vector of disease transmission. Storing sterile mosquitoes in drones and releasing them in targeted areas where previous suppression of wild populations has been performed can be a major advance in this methodology. This is part of the sterile insect techniques (SIT) which have been demonstrated to be an environmentally friendly solution for the control of insect pests. However, the use of drones in the areas where these operations are foreseen is limited by the fact that we have a regulation that advances at a slower pace than technology. Of particular interest is the case of the suppression of mosquito populations in urban areas below the transmission threshold, where drones and their operating conditions must meet demanding safety requirements. This article presents the current regulatory situation in Europe that affects drone operations and its applicability to the case of the release of sterile mosquitoes to control the population of these insects in two different scenarios: urban and rural areas. Abstract: In recent years, several countries have developed the use of sterile insect techniques (SIT) to fight against mosquitoes that transmit diseases. From a technical and economic point of view, the use of drones in the aerial release of sterile mosquitoes leads to important improvements in aerial coverage and savings in operational costs due to the requirement of fewer release sites and field staff. However, these operations are under the European drone regulation, one of the most advanced in the world. The main contribution and novelty of this paper with respect to previous work is the analysis of the SIT application with drones under the European risk-based regulation in two scenarios: urban and rural areas. The specific operations risk assessment (SORA) methodology has been applied to assess the risk of drone operations in these scenarios. The paper presents the operational requirements for aerial release of mosquitoes with drones along with the regulatory considerations that must be applied. Finally, an overview of the conditions in operation that could relax risks and mitigation measures is also discussed. Keywords: mosquitoes’ control; drones; drone regulation; unmanned aircraft systems (UAS); U-space; SORA methodology; sterile insect technique (SIT) 1. Introduction Mosquitoes are considered one of the deadliest reservoirs of vector borne disease in the world. According to the World Health Organisation (WHO), several million of deaths and hundreds of millions of cases occur each year from mosquito-borne diseases. Mosquito control is essential to reduce the transmission of diseases such as malaria, dengue fever, Appl. Sci. 2022,12, 1250. https://doi.org/10.3390/app12031250 https://www.mdpi.com/journal/applsci Appl. Sci. 2022,12, 1250 2 of 15 and Zika. In [ 1 ] the main, mosquito-borne diseases are shown with a summary of statistics and places where mosquito pest control is essential. Different techniques have been used in recent years to control mosquitoes that transmit human disease. Most mosquito control techniques require the use of insecticides with high costs associated in terms of personnel and time. Furthermore, the presence of these toxic products has a large impact not only on human health but also on the environment. Concerns about resistance to pyrethroids in recent years [ 2 ] have led researchers to explore alternative solutions, such as the sterile insect technique (SIT) for mosquito control. The release of sterile insects to contain and suppress [ 3 ] mosquito populations was proposed by Dahmana and Mediannikov (2020) [ 4 ]. This technology has been used for a long time, for example, in 1980 in a program in El Salvador [ 5 ], but the required logistics have limited its applicability in practice. The use of drones is seen as a promising tool for the release of sterile insect populations into targeted environments. Furthermore, these releases are carried out repeatedly over a certain period. The ease of use of drones and their ability to access any environment from the air make them a viable system in this mosquito control technique. Drones may provide a means of releasing sterile mosquitoes over large areas due to the ability of drones to travel long distances in short periods of time. A standard DJI Phantom 4 type light drone can fly for 25 min, being able to travel up to 25 km. Furthermore, one of the main advantages of using drones is that they can reach inaccessible areas where humans cannot. There are some interesting works on this aspect. In [ 6 ] a fully automated system for releasing adult mosquitoes with a DJI M600 drone in a region of Brazil was reported. The system enabled a homogeneous dispersal of sterile male Aedes aegypti while maintaining their quality, leading to a homogeneous sterile-to-wild male ratio due to their aggregation at the same sites. This article concluded that the use of drones for the release of sterile mosquitoes leads to important improvements in aerial coverage and savings in operational costs due to the requirement of fewer release sites and field staff. One of the first works in this direction, dating back to 2017, can be found in [ 7 ] when the WeRobotics organization modified a DJI Matrice 600 drone to integrate a sterile mosquito release mechanism. The effect of storage conditions on the survival of male Aedes aegypti mosquitoes during transport was studied in [ 8 ]. During transport from the rearing facility to the release site and during actual release in the field, damage to male mosquitoes should be minimized to preserve their reproductive competitiveness. The short flight range of male Aedes aegypti requires elaborate release strategies, such as release via drones. The authors conducted shipping in a ‘real-life’ setting to determine a good storage temperature and a compaction rate for the survival of the mosquitoes. In [ 9 ], optimized chilling conditions for handling male adults of Aedes albopictus prior to release were analyzed. The authors claimed that further studies are required to develop drone release systems specific for chilled mosquitoes to improve release efficiency, as well as to compare the population suppression efficiency between release of postchilled and nonchilled males in the field. In any case, the weight of the payload for the UAS was not high and some low-cost solutions [10,11] could be applied. The sterile insect technique is also used to control the codling moth pests and the authors of [ 12 ] evaluated the use of small uncrewed aircraft systems (UAS) for the release of sterile codling moths. Sterile codling moths released from higher altitudes were more widely distributed and drifted more in strong winds, compared to those released from lower altitudes. Most of the released insects were recaptured in a 50 m wide swath under the release route. Recapture rates for aerially released insects were 40–70% higher compared to those released from the ground. The authors claimed that drones provide a promising alternative to ground release and conventional aircraft for the release of sterile codling moths. For the same pest, in [ 13 ] the authors compared the recapture rate of sterile moths following their release by four methods, and the efficiency of each system. The methods were the following: a fixed-wing unmanned plane flying ~40–45 m high at 70 km/h, an unmanned hexacopter travelling 20 m high at 25 km/h, and manually from the ground via Appl. Sci. 2022,12, 1250 3 of 15 bicycles or motor vehicles. The highest recapture rate followed delivery by hexacopter, then bicycle, vehicle, and plane, whereas the methods in ascending order of time per hectare for delivery were the following: plane and vehicle, hexacopter, then bicycle. From an analysis of the state of the art, drone technology is mature enough from a technical point of view to perform the SIT application. However, the use of drones for the release of sterile insects is affected by the new regulation that has been approved at the European level [ 14 ] and came into force in January 2021. Then, the main contribution and novelty of this paper with respect to previous work is the risk analysis needed to put this application in practice with drones in rural and urban areas under the European drone regulation. The European Aviation Safety Agency (EASA) is responsible for implementing, maintaining and monitoring compliance with newly established rules. Historically, each European Union (EU) member state maintained its own drone regulation at national level. Recently, a new EU regulation was approved that affects all member states equally. This new regulation was developed in the spirit of harmonizing rules and promoting the growth of the drone sector. The European regulation applies to any drone regardless of its mass and use. Drone operations are classified according to risk and are broken down into three operational categories. Table 1shows this categorization. Table 1. Categorization of drone operations in the new European regulation. Category Risk Open Low-risk operation Specific Medium-risk operation Certified High-risk operation, similar to manned aviation operations In addition to this, EASA has published the acceptable means of compliance (AMC) and guidance material (GM) [ 15 ], which complement the regulation and explains in detail the different categories set out above. The document entitled Specific Operations Risk Assessment (SORA) details the methodology for assessing the risk of drone operations. In this regard, several papers about risk analysis and SORA can be found in the literature. Reference [ 16 ] analyzes the application of SORA for a multi-UAS airframe inspection (AFI) operation, which involves the deployment of multiple UAS with autonomous features within an airport. In [ 17 ], the authors present the most important risks related to conducting operations with the use of UAS by first responders (FRs), while reference [ 18 ] presents the application of the SORA methodology for media production with a small UAS team. In addition, [ 19 ] describes the application of SORA to the flight of large remotely piloted aircraft systems (RPAS) in Australian airspace highlighting its distinguishing factors. The paper is structured as follows. First, the current European drone regulation will be explained in detail in Section 2. Materials and methods are described in Section 3, where the SORA methodology will be shown as a basis to assess the risk of drone operation and help categorize the operation. Then, the concept of U-Space will be introduced in Section 4since it is the framework that will help integrate drone operations into the airspace. Section 5 explains the results of the application of the SORA methodology to some typical mosquitorelated operations. Finally, Section 6closes the paper with a discussion of the analysis. 2. Current European Drone Regulation As mentioned above, the European Commission adopted a new set of provisions for the use of drones within the Single European Sky strategy, which is an initiative of the European Commission aiming to reform the current air traffic management system in most of Europe. The aim is not only to guarantee standards on the safety, efficiency, and environmental impact of the air traffic, but also to integrate drones safely into airspace. EU legislation has been radically amended in recent years. In July 2018, European lawmakers passed the new Regulation (EU) 2018/1139 on common rules in the field of civil aviation, which included a new mandate for the EU EASA on drones and urban air Appl. Sci. 2022,12, 1250 4 of 15 mobility [ 14 ]. This regulation adopts a new comprehensive legal strategy for the drone sector and repeals Reg. (EC) 2008/216 [ 20 ], which only concerned drones with a take-off weight of more than 150 kg, while drones with a maximum take-off weight of less than 150 kg were within the jurisdiction of the member states. Since neither the EU Parliament nor the EU Council had any objections, both the Implementing and Delegated Acts (Commission Delegated Regulation (EU) 2019/945 [ 21 ] and Commission Implementing Regulation (EU) 2019/947 [ 22 ]) were published in June 2019 and entered into force on 1 July 2019. Drone operators were required to register either in the member state of their residence or where the drone operator registered their main place of business by July 2020. These regulations were gradually enforced over the course of a one-year transition period from their date of publication. This transition period provided Member States and drone operators with time to prepare before full regulatory enforcement in 2022. The new EU regulatory framework covers all types of existing and future drone operations, enabling operators—once authorized in their state of registration—to freely circulate between Member States. The purpose of introducing these new regulations is to ensure the safety of drone operations, as well as to protect the privacy of EU citizens, with respect to personal data protection and the environment while allowing free access to airspace. The new regulations establish technical and operational requirements, provisions for drone operations, and personnel (minimum requirements and operator training), including both pilots and organizations. The EU regulatory framework defines drone capabilities, types of operation and labels these into three broad risk-based categories (open, specific, and certified) following the distinction suggested by EASA in the Opinion 01/2018 [ 23 ]. These three categories of operations are based on the levels of risk involved per drone flight, and each adopts a varied regulatory approach, with drone flight operational limitations decreasing with the requirement for greater authorization from a member state’s national aviation authority. Regulation 2019/947 presents a comprehensive system of unified legal regulations that classifies drone operations into the above-mentioned three categories based on different criteria: • Open (Article 4 of Regulation 2019/947). Operations in this category shall not be subject to any prior operational authorization, nor to an operational declaration by the drone operator before the operation if the following conditions are met. The drone belongs to one of the classes set out in the Delegated Regulation (EU) 2019/945 or is privately built or meets the conditions defined in Article 20 of Regulation 2019/947. The unmanned aircraft has a maximum take-off mass of less than 25 kg, and the remote pilot keeps the unmanned aircraft in visual line of sight (VLOS) conditions at all times except when flying in follow-me mode or when using an unmanned aircraft observer. During open operations, the remote pilot ensures that the unmanned aircraft is maintained within 120 m from the closest point on the surface of the Earth (except when it overflies an obstacle upon request to its owner) and at a safe distance from people (never flying over crowds). The unmanned aircraft cannot carry dangerous goods and does not drop any material. Open operations are further divided into three subcategories: A1 (fly over people), A2 (fly close to people) and A3 (fly far from people). • Specific (Article 5 of Regulation 2019/947). Operations fall into this category as long as the concept of operation exceeds the limitations defined in the open category. The drone operator shall apply to obtain an operational authorization from the competent authority in the member state where it is registered, submitting a risk assessment including adequate mitigating measures. This risk assessment approach allows handling new technologies and operations such as beyond visual line of sight (BVLOS), fully autonomous drones, urban areas, etc. However, if the operation complies with one of the standard scenarios (STS) defined by EASA, the drone operator shall not be Appl. Sci. 2022,12, 1250 5 of 15 required to obtain the above-mentioned operational authorization, and a declaration (responsible) by the drone operator will be sufficient. EASA has defined two STS: ◦STS01: VLOS operation in a controlled ground area in an urban environment; ◦ STS02: BVLOS operation in a controlled ground area in a sparsely populated environment. Apart from that, an operational authorization or a declaration shall not be required for drone operators holding a light UAS operator certificate (LUC) with appropriate privileges, which is valid in all EU member states without additional demonstrations. • Certified (Article 6 of Regulation 2019/947). An operation is classified as being in the certified category when, according to the risk assessment, the operation cannot take place without a certificate for the operator, a certificate for the airworthiness of the drone, and a license for the remote pilot (unless fully autonomous). In any case, the following operations are within the certified category: operations over assemblies of people with an aircraft of characteristic dimensions of 3 m or more, transportation of people, and transportation of dangerous goods if, in case of accident, they pose a high risk for third parties. In October 2019, EASA published its guidance material (GM) and a description of the means of complying with the regulation (acceptable means of compliance (AMC)). The AMC shed light on how to carry out the SORA, which is required for operation, depending on the ‘specific’ category under scrutiny. Along the same lines, EASA has published some predefined risk assessments as AMC to Article 11, to cover most common drone operations. The intent is to simplify the burden for drone operators, paving the way for the full implementation of the new legal framework. Finally, there are some points to be remarked: there is no distinction between professional and leisure activities with drones or between experimental flights and aerial works. 3. Materials and Methods: The SORA Risk Analysis Methodology In the current regulatory framework for drones or UAS in Europe, a risk-based approach is used to assess the safety of drone operations. The SORA methodology has been developed by the Joint Authorities for Rulemaking of Unmanned Systems (JARUS) and focuses primarily on the specific category. The SORA is a multistage process of risk assessment aiming at risk analysis of certain unmanned aircraft operations, as well as defining necessary mitigations and levels of robustness. The application of this methodology is an acceptable means of evaluating the risks associated with the operation of a drone within the specific category and to determine the acceptability of the proposed operation. In this section, a general description of the SORA methodology is presented. 3.1. Introduction to SORA JARUS pursues a consensus from various national aviation authorities and stakeholders on a common procedure to identify and qualitatively assess safety risks for drone operations. In particular, JARUS developed SORA [24] in 2019. Any risk assessment methodology uses a schema based on the ISO 31000 standard, providing a reference framework and guiding the general risk management process (see Figure 1). Appl. Sci. 2022,12, 1250 6 of 15 Risk assessment Risk identification Risk analysis Risk ev�luation Risk treatment Figure 1. General aspects of risk management from ISO 31000. The risk management process involves the systematic application of policies, procedures and practices to the activities of communicating and consulting, establishing the context and assessing, treating, monitoring, reviewing, recording and reporting risk. SORA is a method based on a holistic risk model that provides a generic framework to identify possible hazards and threats, as well as relevant harm and threat barriers applicable to drone operation. The aim is to establish a sufficient level of confidence that a specific operation can be carried out safely. To achieve this, SORA requires first the applicant to collect and provide the relevant technical, operational, and system information needed to assess the risk associated with the intended operation of the drone. Some key aspects related to the applicability of the methodology are the following. • It aims to assess the safety risks involved in the operation of drones of any class, size, and type of operation and particularly suited, but not limited to ‘specific’ operations for which a risk and hazard assessment is required. • The safety risks associated with collisions between drones and manned aircraft are within the scope of the methodology. • Security aspects are excluded when not limited to those confined by the airworthiness of the systems (e.g., aspects relevant to the protection from unlawful electromagnetic interference). •Privacy aspects are excluded from the applicability of this methodology. 3.2. The SORA Process The SORA methodology provides a logical process for analyzing the proposed concept of operations (ConOps) and establishing an adequate level of confidence that the operation can be conducted with an acceptable level of risk. There are ten steps that support the SORA methodology, as shown in Figure 2. The process begins with the ConOps description, which provides the relevant technical, operational, and system information needed to assess the risk associated with the intended operation of the drone, both ground risk and air risk. Appl. Sci. 2022,12, 1250 7 of 15 Figure 2. The SORA process adapted from [ 24 ] shows the ten steps that support the SORA methodology. The ground risk class (GRC) is the intrinsic ground risk of the drone related to the risk of a person being struck by the drone (in the case of loss of drone control with a reasonable assumption of safety). To compute it, the applicant needs to identify the maximum drone characteristic dimension (e.g., wingspan for fixed wing, blade diameter for rotorcraft, maximum dimension for multicopters, etc.) and the knowledge of the intended operational scenario (VLOS or BVLOS; population density of the overflown areas). Intrinsic risks can be controlled and reduced by mitigations. The mitigations used to modify the intrinsic GRC have a direct effect on the safety objectives associated with a particular operation and, therefore, are important to ensure its robustness. The final determination of the GRC is based on the availability of these mitigations for operation. The air risk class (ARC), understood as the intrinsic risk of mid-air collision, determines the air risk category. Identification of the ARC must take into account the impact on other air traffic and air traffic management (the altitude of the operation; controlled versus uncontrolled airspace; aerodrome versus non-aerodrome environment; airspace over urban versus rural environment). The ARC may be lowered by applying strategic and tactical mitigation means (detect and avoid systems or alternate means) resulting in the residual ARC. Strategic conflict strategies will deal with the planning at a global level of the route that the drone must follow to execute the mission, while tactical conflict strategies will deal with reactive local maneuvers that are executed during the flight to fulfill certain functionalities, such as avoiding possible encounters with other aircraft. After determining the final GRC and residual ARC, it is now possible to derive the specific assurance and integrity levels (SAIL) associated with the proposed ConOps. The Appl. Sci. 2022,12, 1250 8 of 15 SAIL represents the level of confidence that the operation will remain under control. On the other hand, the SAIL is also used to evaluate the defenses within the operation in the form of operational safety objectives (OSO) and to determine the associated level of robustness. These OSOs appear in the SORA as a list of objectives that have historically been used to ensure safe drone operations regarding technical issues, external systems supporting the operation, the effects of human errors, and the effects of adverse operating conditions. In this paper we address two different scenarios that are highly representative of mosquitoes-related operations. First, it is considered the case of an urban environment targeted for a SIT mosquito program. Usually, large cities and their surroundings are immersed within the airspace associated with airports. Therefore, the operation is considered to be carried out in controlled airspace. The following conditions for the urban scenario constitute the ConOps for this case: •VLOS: The operation takes place within the visual line of sight of the pilot; •Moderately populated environment; •Inside of controlled airspace; •VLL: very low level operation, flights below 150 m of altitude. The other case is in rural environments, without people around, which are aligned with population control in areas where this type of insect reproduces: lakes, humid areas, areas with dense vegetation, etc. In this case, the operational conditions that are considered as inputs for the ConOps are the following: • BVLOS: the operation takes place beyond the visual line of sight of the pilot, without observers who can help the pilot; •Sparsely populated environment; •Out of controlled airspace; •VLL: very low level operation, flights below 150 m of altitude. 4. Integration into Airspace (U-Space) As indicated in [ 25 ], the expected number of drone operations in the European market is expected to reach 10 billion euros per year by 2035 and more than 15 billion euros per year by 2050. This volume of operations will pose safety, security and airspace integration issues in European airspace, especially at low flight levels (which are currently defined as altitudes below 150 m) with drones belonging mostly to open and specific categories. Many organizations are iteratively maturing their approach to address this volume of drone operations, as outlined in various concepts developed by bodies such as the Single European Sky Airspace Research (SESAR) Joint Undertaking (JU) through the CORUS project [ 26 ], the Federal Aviation Administration (FAA) [ 27 ], and global standardization bodies such as the Global UTM Association (GUTMA) [28]. In Europe, safe drone traffic management and its safe operation within the existing air traffic environment in a harmonized manner across the European airspace are ensured by U-space (outside Europe, this concept is commonly referred to as unmanned traffic management or UTM). In [ 29 ], SESAR JU defined U-space in a blueprint as a set of services based on high levels of digitization, as well as automation of functions and procedures designed to guarantee access to airspace for a large number of drones in a safe and efficient way, with an initial focus on operations at very low levels (VLL), with a maximum height above ground level of 150 m. Then, U-space is a technological framework designed to facilitate any type of operation, in all classes of airspace and in any environment, even the most congested, while providing an appropriate interface for manned aviation and air traffic control. The ConOps (concept of operations) for U-space was developed in the CORUS project and published on 30 September 2019 [ 26 ]. CORUS was focused on drones belonging to open or specific categories that operate in VLL, which are split into three types according to the services provided (see Figure 3): •X: No conflict resolution service is offered; Appl. Sci. 2022,12, 1250 9 of 15 •Y: Only preflight conflict resolution is offered; •Z: Preflight conflict resolution and in-flight separation are offered. Figure 3. Classification of airspace adapted from the CORUS project [ 26 ]. The VLL airspace is divided into X, Y, Z volumes: X (low risk), Y (higher risk—access only with approved operation plan and specific technical requirements per volume) and Z (highest risk—access only with approved operation plan being Zu under U-space and Za the ATC controlled airspace). Type Y airspace will be available from U2 and will facilitate VLOS, EVLOS (extended visual line of sight) and BVLOS flight. The risk mitigations provided by U-space mean that the Y airspace is more amenable to other flight modes than X. Type Z airspace may be subdivided into Zu and Za, controlled by UTM and air traffic management (ATM), respectively. Za is simply a normal controlled airspace and is therefore immediately available. Zu airspace will be available from U3. Because U-space provides more risk mitigations for Z type, it is more amenable to other flight modes, and allows higher density operations than Y airspace. Z allows VLOS and EVLOS and facilitates BVLOS and automatic drone flight. Finally, EASA issued Opinion No 01/2020 [ 30 ] on 13 March 2020, which proposed a draft of the high-level regulatory framework for U space, closely linked to the two existing drone regulations [ 21 , 22 ]. The opinion proposed a first set of what were considered by EASA as the minimum necessary rules, which are to be complemented later with further provisions enabling a more mature state of airspace integration. The objective of the opinion was to create and harmonize the necessary conditions for manned and unmanned aircraft to operate safely in the U-space airspace focusing on strategic and pretactical traffic management techniques in order to mitigate the risk of collisions by requiring adapted services and sharing essential traffic information. In this sense, the opinion acknowledged that ensuring that U-space participants are cooperative is required until further development of detect and avoid (DAA) systems to ensure safe operations, in particular for BVLOS operations. The airspace in which aircrafts fly can be classified as controlled airspace in which air traffic control (ATC) services such as clearance and traffic information. However, in uncontrolled airspace, there are no such services for manned aircraft. With the integration of U-Space in the future, when the member states designate a volume of airspace as U-space airspace, there will be a restriction: both for drone operators, to use U-space services to fly in that airspace; and for manned aircraft operators, to make available their position at regular intervals.