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I. INTRODUCTION
UAM (Urban Air Mobility) is a future air transportation system that operates in urban areas. For establishing a safe system of future air transportation, UAM operation requires extensive research and preparation. Before the establishment of the UAM system, it is essential to conceptualize the UAM operation philosophy, and to establish a UAM flight philosophy so hazards can be avoided beforehand.
Currently, the domestic UAM operating environment is in the preparation stage, and related industries are conducting research on the development of aircraft in Hyundai Motor Group and Hanwha System, as well as research into the operating environment of UAM conducted by the government and research institutes. According to the government’s K-UAM Roadmap1) for the UAM era, autonomous flight requires pilots. Therefore, research applying the pilot’s actual operating experience and procedures will be very effective in establishing a UAM safe operating environment.
Concerning UAM, the following definitions apply. The FAA (Federal Aviation Administration) defines an unmanned aircraft as a device that is used or intended for use in the air without an onboard pilot. This device excludes missiles, weapons, or exploding warheads, but includes all classes of airplanes, helicopters, airships, and powered-lift aircraft without an onboard pilot. It is a mobile aircraft used for flight without an onboard pilot. In addition, it specifies that it includes all types of aircraft, helicopters, airships, and powered buoyant aircraft without pilots. The classification of unmanned aircraft is based on the first edition of the RPAS manual (2015), which is divided into “Remotely Piloted Aircraft (RPA)”, “Autonomous Aircraft”, and “Model Aircraft”. A Remotely Piloted Aircraft is an unmanned aircraft controlled by a remote control station, while an Autonomous Aircraft is an unmanned aircraft without any pilot interaction or involvement in flight operations (Kim et al., 2017). Pilots are still required from the point of commercialization of UAMs to the point of complete autonomy and unmanned operation. According to the UAM technology Roadmap of the Ministry of Land, Infrastructure and Transport, pilot operation is essential from the stage of preparing the commercialization base to the preparation for the commercialization (2025- 2029) stage and the growth period (2030-2034). Yet it has not yet been discussed whether pilots suitable for UAM operations should be selected and trained. However, it should be noted that the UAM operating environment and the technical system of the existing transport aircraft are not significantly different and that the experience accumulated in the macro-flight environment can be prepared by applying it to the micro-flight environment of the UAM operating system. The purpose of this study aims to provide a plan on how to best prepare and train pilots who will be most effective in UAM flight environments.
Research and regulation for UAM aircraft are currently focused on VTOL (Vertical Take-off and Landing) aircraft, which combine rotary and fixed wings to provide economic feasibility. However, the development of VTOL aircraft and related UAM certificates is not based on an understanding of flight principles, flight control technology, or flight environment. A certificate is a dangerous idea since it aligns with the technology development trend, that is, aircraft.
In the case of Europe, The European Aviation Safety Agency (EASA) classifies VTOL-type airframe into new types. In the case of the United States, The FAA is promoting a plan to qualify the VTOL model according to its form by classifying it as a type certificate in 14 CFR 61 61.31. This study, however, does not take into account eligibility criteria based on the new airframe, such as VTOL. The UAM flight system, including the International Aviation Organization (ICAO), is said to be similar to the rotorcraft flight system (Kim et al., 2022). The answer to granting this, UAM eligibility criteria are given. Flight control is not an area of classification according to the type of aircraft. This is because the control technology does not vary based on the type of aircraft. UAM should be reviewed by focusing on the operating environment rather than on the qualification criteria related to flight operation.
II. ENVIRONMENT OF UAM FLIGHT OPERATION
UAM aircraft is a complex operating system that requires overcoming topography, obstacles, and weather conditions in urban areas and ensuring safety. A safety plan should be established in this operating environment by anticipating risk factors that have not yet been identified for paid operations through UAM commercialization.
There are many unfavorable factors in the UAM operating environment. UAM operations are low-altitude flights, which must precede the risk of collision and the safety of the aircraft. Our analysis of the UAM operating environment consisted of measuring the required navigation performance (RNP) of the route and approach sections by operating the actual B737 flight.
As a result of the experiment, Tables 1 and 2 were measured by B737 aircraft, showing the level of active navigation performance (ANP) of 0.02 in the RNP 2.0 section (Choi et al., 2021). This shows that more precise system development and pilot training are required to satisfy the RNP 0.01 level of UAM-only routes designed by UBER (Bradford, 2020).2)
ICAO Annex 19 explains the definition, background, and concept of SMS (Safety Management System). The development of a complete system is impractical, but internalizing a safety- oriented philosophy can reduce predicted risks by identifying hazards ahead of time.
ICAO recommends the SMS model as a standard model by issuing ANNEX 19 through four revisions from 2006 to 2018. SMS aims to promote operational safety by identifying Hazard in the operating environment, classifying them according to Safety Risk, and removing Hazard in advance. This methodology will be appropriate as a way to promote aviation safety by predicting the Hazard constituting the UAM ecosystem in advance. As a result of this study, pilots who are responsible for promoting UAM operation safety will be able to identify hazards before UAM design and then apply SMS concepts to their training and training pilots.3)
III. DIRECTION OF UAM OPERATIONAL QUALIFICATIONS AND TRAINING
The criteria for UAM aircraft are important challenges as they become the criteria for training and selecting UAM pilots. The current type of airplane can therefore accommodate pilot training.
Therefore, UAM trainees, fixed-wing airplanes, rotor wing airplanes, and drone pilots can be reviewed in the selection of pilot training.
There is usually no difference in the flying skills of aircraft control regardless of the type of aircraft. Especially in military education institutions, it is common to see that Skill for aircraft control has common skills, but there is a difference in technic used in the operating environment.
Therefore, considering the market environment in which UAM aircraft is being developed as a composite according to fixed wing, rotorcraft, or drone technology, the categories of selection targets required to train UAM pilots are those with basic understanding and control skills (Park et al., 2014).
The UAM operating environment is accompanied by the flight methods of visual flight rules (VFR), instrument flight rules (IFR), and essentially performance-based navigation (PBN). Pilots who have UAM capabilities must also have PBN capabilities.
First, UAM pilots must be equipped with control techniques that skillfully handle UAM aircraft. Second, UAM pilots must have the ability to VFR and IFR. Third, UAM pilots must have an understanding and operational capability for PBN navigation. Fourth, UAM pilots must have the ability to overcome crises in abnormal situations.
As part of UAM, fixed-wing aircraft, rotor wings, and drones will be developed. As a result of these development trends, UAM aircraft are classified into airplane types and designated with Type Ratings. Overseas, there is a tendency to classify airplanes by complexity, but this method might confuse when training early UAM pilots. To reduce confusion and train efficient pilots, it is appropriate to maintain Article 34 and Article 35 of Aviation Safety Act Chapter 4 and to classify and grant UAM aircraft as type certification. Furthermore, it is necessary to strengthen the minimum qualifications for people who are capable of overcoming crises in abnormal situations, such as advanced navigation equipment, the volume of airplanes, and crisis-resilient skills. According to Table 3, a verification system is set up for each step of the UAM roadmap once the concept of the UAM pilot qualification criteria is defined.
The characteristic of the UAM system is that it is exposed to a low altitude, urban-dense operating environment. To address this, it is necessary to develop an education and training system. Several factors limit maneuvering and navigation in the UAM environment, such as obstacles, navigation equipment, TCAS (Traffic alert and Collision Avoidance System), and low visibility weather conditions. According to the 2013 helicopter crash analysis results of LG Electronics, the accident occurred due to low altitude strong gusts, and low visibility even though the accident aircraft was equipped with a TCAS and autopilot control devices. Therefore, pilot training should be conducted by setting a systematic UAM flight operation environment and effective program, and curriculum (KBS News, 2015).
It is important to establish UAM pilot qualification criteria based on the operating environment and the pilot’s essential requirements. The exact literature for UAM pilot eligibility criteria is the PIC definition of FAA UAM Conops.4) When applying this, UAM aviation personnel shall apply to the Aviation Safety Act, Chapter 4, Aviation personnel, etc., Article 34 (Certificate of qualification for aviation personnel, etc.), and Article 35 (Type of qualification). In particular, concerning PIC concept presented in FAA Conops and the definition of a pilot given in Article 63 of the Aviation Safety Act, the minimum qualification criteria for early UAM operators should be considered as transport pilots and qualified equivalent to PIC. In addition, it is necessary to review the minimum qualifications as a person with performance-based navigation experience and sub-functional abnormal situations. A person with performance-based navigation experience and subfunctional abnormal situations must also review the minimum qualifications.
Therefore, according to Table 4, training and certifying UAM pilots as qualified persons for Commercial License PICs of small air transport operators or aircraft users is effective.
| Classification | Certification |
|---|---|
| Fix wing | Commercial License or ATP |
| Rotor wing |
The UAM operator will select the aircraft to be used in the transportation business. In the UAM transportation business, as part of UAM’s transportation business, aircraft qualifications are granted based on aircraft selected by operators. Hanwha System and Hyundai Motor Group are developing the UAM aircraft as a VTOL, but research and development are underway as a fixed-wing aircraft as well. In summary, in accordance with Table 5, the pilot can obtain a type rating for the model selected by each UAM operator with the fixed wing and rotor blade certificate as a joint qualification.
| Classification | Certification |
|---|---|
| Fix wing | Type rating |
| Rotor wing |
Pilots who have UAM capabilities must also have VFR, IFR, and PBN capabilities. For UAM aircraft to operate at low altitudes, an environment based on performance-based navigation, communications, navigation surveillance, and information (CNSi), and required navigation performance (RNP) must be provided. A concept that secures navigation safety by applying the concept of maritime airspace communication performance and performance-based navigation to aircraft capable of long-distance operations between continents.
Additionally, UAM airspace takes into account the operating environment and restrictions. Considering weather, airmass, and obstacle restrictions, routes should be built using existing performance-based navigation systems like the Global Navigation Satellite System (GNSS), RNP, and IMU. The initial stage of development is likely to be GNSS-based. In the civil aviation sector, the “Differential Global Positioning System (DGPS)” is used to improve the accuracy of GNSS. Therefore, the supply and demand of prepared personnel to use these advanced navigation and information systems are essential for the safe flight of UAM. Urban Air Traffic Management (UATM) is operated based on data communication, so it is expected that required communication performance (RCP) and required surveillance performance (RSP) technologies will be applied. The concepts of the two technologies are shown in Figs. 1 and 2.
The direction of training should be to develop crisis management training for weather consideration and obstacle avoidance and to ensure safety by organizing training, regular training, and evaluation. The training of UAM experts should be conducted through essential training, non-essential training, evaluation system development, and training certification based on the operating environment. In particular, the establishment of contingency procedures should be subdivided into weather condition analysis and emergencies. During the early stages of development, the UAM airspace will be operated as a satellite navigation system. A skillful use of advanced navigation equipment is therefore necessary.
Early stages of development require examining whether it can be applied to low altitude airspace for UAS Traffic Management (UTM). In civil aviation operations, NON-normal situations are frequent due to receiver autonomous integrity monitoring (RAIM) problems. Solving this problem requires the development of situational action training at the same time.
As well as evaluating skill and competency, UAM pilots are extremely important. UAM pilots should always ensure operational safety and maintain the skills and capabilities to protect human life. Therefore, the evaluation system for this should consist of regular examination, simulation training, and SMS training.
IV. CONCLUSION
A pilot will be responsible for controlling the flight of the UAM in the initial phase of UAM technology development. The act of flying is directly related to human life as well as a priority for safety. In order to prevent flight accidents, safety factors must be considered in detail.
The UAM environment is a human challenge against nature and the courage to confront dangerous environments with technology. Civil aviation continues to experience safety accidents despite the latest technology, and UAM development will face greater safety challenges. The current act can serve as a lesson for preventing this in the future. As a crystal of perfect high-tech, UAM will operate in the human realm until a perfect gas, AI, and navigation technology are developed.
Training UAM pilots as qualified personnel for Commercial License PIC of an aircraft operator or small air carrier would be effective. The pilot must also obtain a Type Rating for the model selected by each UAM operator and a fixed wing and rotor blade certificate. Navigation training for low altitude flight, which is characteristic of UAM, and gastric functional training should be included in education and training. Legal evaluation for flight competency maintenance and development is continued.
Lastly, we emphasize the establishment of a risk-based safety system for successful UAM system construction and look forward to the development of pilot training, normal operation procedures, and operation capability of performance-based navigation.
