The popularity of Remotely Piloted Aircraft Systems (RPAS) is growing at an increasing rate as an alternative to manned aviation for different purposes and applications. So far, most of their operations have been of military character, but the demand for civil and commercial applications is growing exponentially. RPAS have been allowed to operate in segregated airspace by restricting other users from entering the volume associated to the operation of the RPAS. This temporary solution based on accommodating their operations on a case-by-case basis is not feasible on the long-term. Moreover, the latest forecast carried out by SESAR Joint Undertaking (SJU) reveals that by 2050 RPAS will represent 20% of the fleet. The available airspace is a scarce resource and is already saturated, which means that additional unmanned operations would not be possible
simultaneously. Integration in non-segregated airspace is the only manner in which the full benefits and capabilities of RPAS will be achieved, while maintaining the same levels of safety and efficiency as manned aviation.

In order to achieve a safe, efficient and transparent integration, a common regulatory framework and new technologies are currently under investigation. However, neither operational nor performance standards of RPAS integration have been addressed properly. For that reason, this project is focused on the development of a methodology to determine minimum operational and performance requirements by assessing the impact of RPAS operations on the Air Traffic Management (ATM) Network. The scope is limited to the en-route phase as a starting point since none of the flight phases have been analysed yet. This project is carried out in collaboration with EUROCONTROL.

RPAS are well known for presenting a wide range of performance characteristics, especially in terms of cruise speed and rate of climb. Thus, two different unmanned performance models have been chosen from the available performance models in the EUROCONTROL database: RP01 (MQ-9), which presents a similar performance to commercial aviation aircraft, and RP02 (RQ4A), which is considered a low-performance
RPAS in terms of cruise speed and rate of climb. Building on a base scenario in the Paris Control Terminal Area (CTA),Monte Carlo simulations of the air traffic have been performed in order to randomly vary the main input variable: the set of en-route flights that is substituted by unmanned aircraft. Two different scenarios have been analysed separately in order to establish the requirements: one for same-performance RPAS, and the
other for low-performance RPAS. In order to assess the impact, three different Key Performance Areas (KPAs) have been selected: capacity, efficiency and safety. These KPAs are in turn characterized by their corresponding Key Performance Indicators (KPIs), namely sector capacity, sector overload, flight time efficiency, flight path efficiency and number of potential conflicts.

Based on an analysis of the current occupancy of the flight levels, operational requirements are defined in terms of altitude segregation. RPAS are not allowed to operate in the most occupied flight levels (FL): from FL300 to FL400. Therefore, depending on their operation and performance characteristics (i.e. ceiling), they will adapt their cruise FL to operate below FL300 or above FL400. The optimal value of performance requirements for same-performance RPAS has been found to be a minimum cruise speed of 390 kts, while for low-performance RPAS this minimum cruise speed is of 280 kts. Additionally, for low-performance RPAS, it is found that the rate of climb of 1,000 fpm results in the best performing case when changes in FL are required.

The results show that the values of the key performance indicators for the base scenario are difficult to reach when RPAS are sharing the airspace. However, the establishment of minimum operational and performance requirements contributes to a significant reduction of the negative impact that the integration of RPAS operations implies.

The development of this methodology and its application to the characteristics of each airspace sector will contribute to the full integration of RPAS in non-segregated airspace.

Remotely Piloted Aircraft Systems (RPAS) are becoming more and more popular with an increasing number of companies using them in the fields of precision agriculture, emergency delivery of medical aid and preventive maintenance. Trials are being made to extend their use to public safety, monitoring traffic, providing internet and even air taxi services. These RPAS operations are currently handled on a case-by-case basis and operated in segregated airspace by creating temporary restricted areas for other traffic. With the SESAR Joint Undertaking (SJU) estimating that in the next 30 years 20% of the traffic will be remotely piloted, the option of airspace segregation will no longer be feasible. Therefore, integrating RPAS with current manned operations will be required. In doing so, however, the current levels of safety and efficiency should not be compromised. The command and control link (C2), which connects the remotely piloted aircraft and the remote pilot station, plays a pivotal role in the controllability of the aircraft, ATC communication and conflict detection and avoidance systems (CD&A). This project, which is conducted between Delft University of Technology and EUROCONTROL, aims at establishing a methodology of determining how different percentages of flights that are remotely piloted and different C2 link failure rates influence the number of separation losses (blind encounters). For this, fast time simulations of a 24-hour period of the Dutch airspace are performed in AirTOp. This study will contribute to the integration of RPAS in non-segregated airspace and will serve as an input for the regulatory bodies which are yet to set performance standards on RPAS, particularly the C2 link. Replacing between 10 - 50% of the flights in the Dutch airspace by RPAS with failure rates of the C2 link of 0.01 - 0.001 resulted in 1 - 15 flights being replaced by an RPAS with C2 link failure. This generated an additional number of blind encounters between 1.8 - 23.6, or an increase of 0.09 - 1.18% compared to the baseline situation (same traffic, no RPAS). Also, a linear relationship was found between the number of RPAS experiencing a failure of the C2 link and the number of blind encounters. The project also investigates how an RPAS that experiences a failure of the C2 link right at the moment when it enters an ATC sector in Langen FIR (EDGGPHHM) penalizes key ATM performance indicators. The considered KPIs are: number of potential conflicts, air traffic controller task load, sector occupancy, distance flown, flight time, fuel consumption and altitude deviation. The scope is limited to en-route operations above 500 ft and the contingency strategy followed by the RPAS once it loses the C2 link is to proceed to its destination along its originally submitted flight plan. At the same time, air traffic controllers would enforce a separation bubble around the RPAS, such that a buffer is created for the situations in which the remotely piloted aircraft might deviate from it route or behave erratically. Two RPAS performance models are considered: MQ-9 Reaper, a turboprop with a lower cruise speed and climb/descent performance than current civil aircraft and RQ-4A Global Hawk, a turbofan with a cruise speed close to that of civil aircraft and a rate of climb slightly higher. The results of the Monte Carlo tests are analyzed using ANOVA and MANOVA tests. Increasing the size of the separation bubble around the RPAS with C2 link failure by 20%, 40% and 60% resulted in an increase in the number of potential conflicts of 8.3%, 9.2% and 12.0% when a MQ-9 was used. The impact on controller task load was found to be small (increase of 0.4%) and not affected by the size of the separation bubble. Similarly the other KPIs were not affected by a separation increases of up to 60%. Switching 10-30% of the flights to RPAS and using even larger sizes of the separation bubble (twice or three times as large as the minimum ICAO standards) increased the number of potential conflicts by up to 72.9%, sector occupancy by 11.2% and the additional time spent in the sector by 1.4%. Based on the separation requirements which will be enforced around RPAS, the methodology used in the report can be used to assess the impact of experiencing a C2 link loss on the ATM environment.