EUROCAE ED-253 PDF

Remotely Piloted Aircraft Systems (RPAS) operations are currently performed in segregated airspace or under strict conditions of operation. Their safe integration into the airspace (Controlled and non-controlled airspace (class A to G); i.a.w. Instrument Flight Rules (IFR) / Visual Flight Rules (VFR), under Instrument Metrological Conditions (IMC) / Visual Metrological Conditions (VMC)) will improve their benefits for operations and enable their expected use by civilian operators. However, many substantial barriers, including technical issues, certification and regulation changes, and legal and social concerns, must be overcome before widespread use of RPAS in civil aviation is possible.

RPAS is a subcategory of Unmanned Aircraft Systems (UAS) that has a Remote Pilot (RP) controlling and monitoring the aircraft from a remote position. The term system refers to the complex nature of RPAS, where a Remotely Piloted Aircraft (RPA) is piloted from a Remote Pilot Station (RPS) utilizing a command and control (C2) link. Together with other components such as launch and recovery equipment, if utilized, the RPA, RPS and C2 link comprise an RPAS.

RPAS and their interactions are depicted at a high level in FIGURE 1.1, including those possible interactions with the environment and other Airspace users (civil manned aircraft, military aircraft...).

NOTE: The C2 link includes the direct communications links as well as the relay links.

If RPAS are to be integrated, either for civil or military applications, they will have to comply with the same rules and procedures as the other airspace users, without degradation of the level of safety, or disruption of current operations or modifying air traffic control (ATC) procedures. Therefore, it is considered that RPAS behaviour in operations must be equivalent to manned aviation, including interaction with ATC.

RPAS must adhere to the rules of the airspace and must comply with the communication, navigation and surveillance (CNS) requirements in Air Traffic Management (ATM) context applicable to the class of airspace within which they intend to operate. This includes providing corrective actions and flight information in real time, maintaining position between two points of the trajectory, and verifying that the aircraft is where it should be. RPAS must also meet supplementary certification requirements to fly under specific conditions (e.g. flight into known icing conditions), if their typical mission profile will involve such conditions.

Challenges in airspace integration are related to the fact that the RP is physically separated from the RPA, resulting in a reduced situational awareness, limitations in operating and monitoring the RPA’s systems (i.e. in case of C2 link interruption or loss, but possibly also by design), and delays introduced by the C2 link. These factors contribute to the RP’s workload and limit the ability to effectively react to situations.

Automation is the way to safely relieve the aircrew of some routine duties thereby reducing fatigue (e.g. by autopilots, auto thrust, auto brake, navigation system). Acceptable Means of Compliance (AMC) 25.1302 – Appendix 2 states that "automation is the autonomous execution of tasks by aeroplane systems started by a high level control action of the flight crew". The intended RPAS automation capability is also expected to be used as a backup strategy to safely cope with the lack of a human in the control loop especially during contingencies, e.g. loss of C2 link, and emergencies. Generally, limits and risks associated with increased levels of automation must carefully be assessed. Especially, Human Factors must be considered. International Civil Aviation Organization (ICAO) Circular 249-AN149 “Human Factors in CNS ATM Systems” provides guidance in this area.

The basic workload tasks of the minimum flight crew considered in the Certification Specification (CS) 25.1523 as adapted for RPAS, are the following:

• Flight path control.

• Collision avoidance.

• Navigation.

• Communications.

• Operation and monitoring of RPAS components.

• Command decisions.

In the RPAS automation context, these pilot-related functions will be allocated to either a RPS or a RPA or to both. Neither of these functional allocation strategies is part of the assumption basis of the current regulations and standards, yet their use must provide a level of safety equivalent to that of manned aircraft operations. Throughout this document the only flight crew member identified is the RP. There is nothing in this documentation to prevent the creation of other flight crew roles, providing the definition and operation of the RPAS complies with the rules of the air.

The European RPAS Roadmap published by the European RPAS Steering Group (ERSG) states:

”…The R&D effort to close the identified operational and technology gaps will include the need to develop operational procedures, technical systems models or prototypes leading to proposed standards in parallel, but clearly linked to the development of regulations and standards for the safe and efficient integration of RPAS…”

The scope of the A&ER function is limited to those phases where operational responsibility is with the RP.

Additional operations done before "Handover to Remote Pilot" or after "Handover to Ground Crew" such as maintenance procedures, mission planning, etc. are considered beyond the scope of this OSED. Aspects beyond the scope of the A&ER function (but their existence in the RPAS is expected) are:

• Avoidance Manoeuvres which are defined by other subsystems, e.g. Detect & Avoid (DAA) for intruder avoidance and, as far as required by the mission profile, weather and terrain avoidance (however, A&ER needs to prioritise between conflicting information from those subsystems).

• Standard flight guidance and control functions like flying standard turns, following the planned route, acquiring and holding target values for altitude, heading, etc., as detailed in Aeronautical Radio, Incorporated (ARINC) 702A standard;

• Sensing, identifying and isolating subsystem failures;

• Detection of events e.g fire, bird strike, hard landing, lightning strike, severe turbulence, unusual vibration, hail and icing;

Further, the following aspects are considered beyond the scope of the A&ER function and not expected in an RPAS:

• Voice recognition and synthetic voice communication;

• Task that cannot be automated with current state-of-the-art technology;