１．Aviation Rule Essential to HAPS

HAPS (High Altitude Platform Station) represents a revolutionary system that harnesses cutting-edge technologies including an ultra-lightweight airframe structure, high-performance electric propulsion motors, as well as solar power and high-performance batteries. This makes possible the special operation of long-duration flights at higher airspace (>60,000 feet/approx. 18 km). The unique characteristics of HAPS pose challenges in complying with existing aviation rules, necessitating the development of new regulations to enable its commercialization.

In this context, SoftBank actively participates in the development of the aviation system, striving to establish favorable rules tailored specifically for HAPS operations.We firmly believe that the establishment of appropriate aviation rules is paramount to maintaining our competitiveness in the global market. In this article, we delve into the current structure of the aviation system and highlight the progress made by SoftBank in shaping the new regulatory framework. By sharing these developments, we aim to underscore the importance of this initiative and showcase our ongoing efforts in advancing the HAPS industry.

2. The State of Aviation Rules Sorrounding HAPS

At the pinnacle of civil aviation rules lies the Convention on International Civil Aviation (known as the Chicago Convention), which was established back in 1944. Following its conclusion, the International Civil Aviation Organization (ICAO) was established in 1947. ICAO, along with national authorities, is responsible for formulating international aviation rules.

The Chicago Convention and its annexes encompass two essential components: "International Standards," which are binding for all parties, and "Recommended Practices," which serve as guidelines for implementation. Collectively, these elements are referred to as "SARPs" (Standard and Recommended Practices).To ensure compliance, each country adheres to ICAO-SARPs and develops national legislation accordingly. Proposed modifications to ICAO International Standards (SARPs) can be submitted either by national authorities or ICAO ANC Observers during ICAO meetings. Direct proposals from private companies are not accepted.

Three Pillars of International and Domestic Aviation Rules

・Aircraft Safety (Airworthiness Certification)
・Pilot’s Skill (License/Certification)
・Operating Rules of the Air

The existing aviation rules have been formulated under the premise that both pilots and passengers will be physically present within the aircraft. In contrast, HAPS offers the following distinct features:

Uncrewed Remote Control (with autonomous flight as a future goal)
Extended High-Altitude Flights (60,000 ft/18 km or higher)
Cutting-Edge Technological Elements: HAPS incorporates an ultra-lightweight airframe structure, solar power and high-performance batteries, and high-performance electric propulsion systems, among other technological advancements.

As such, since HAPS significantly differs in many aspects from the aircraft envisioned in existing aviation rules, the development of new regulations is necessary. In relation to HAPS activities, as shown on the left in the figure below, there is a Remotely Piloted Aircraft Systems Panel (RPASP) within the ICAO organization. Activities started in 2015, and under the RPASP, there are Working Groups (WG) in each field as shown in the center of the figure below. They are progressively revising the Standards and Recommended Practices (SARPs). Ultimately, the revision process is aimed to be completed by 2026.

However, while HAPS falls under the broad category of Remotely Piloted Aircraft Systems (RPAS), the RPASP's focus is primarily on remotely piloted aircraft (an engine aircraft remotely piloted by a single pilot for one airframe)
operated under instrument flight rules (IFR), excluding HAPS or stratospheric operations. Due to work priorities, HAPS currently remains on a waiting list for inclusion in the RPASP's agenda.

3. Aviation Rule Formation Strategy

The contributions made by each country, standardization organizations, and companies play a crucial role in shaping international rules under the auspices of ICAO. However, proposing changes independently may not suffice; strategic involvement is vital to advance international rule-making processes. In this regard, SoftBank adopts the following two strategic approaches:

・Individual Activities with Partner Companies
・Joint Activities through Private Organizations

In both of these approaches, active involvement is crucial to safeguarding business development by preventing the implementation of adverse regulations. To align with the foundational "three pillars," we employ specific strategies for rule-making as follows:

■Aircraft Safety (Airworthiness Certification)

Key point 1：Collaborative engagement with manufacturers: joint participation in FAA meetings, tests, and audits

As of now, no large fixed-wing aircraft in the HAPS category has obtained official airworthiness certification. In pursuit of this certification, SoftBank's development partner, AeroVironment, has submitted an application for type certification to the Federal Aviation Administration (FAA), with SoftBank actively collaborating as the operator to obtain type certification.
The partnership between SoftBank and AeroVironment reflects a similar approach seen in the "Working Together" model adopted by manufacturer Boeing and operator ANA for the development of B-787.

*Working Together: An approach where aircraft manufacturers and customers build a cooperative relationship, leveraging each other's strengths to jointly develop from the early stages of design.

Key point 2：The development of new standards is a crucial aspect that will shape the standards for future HAPS large fixed-wing aircraft.

Certification Basis (Applicable standards :airworthiness, etc.)
To address elements not covered by existing standards, such as ultralight airframe construction, solar power, high-performance batteries, high-performance electric propulsion motors, and long-duration flight, the need has arisen for the development of new standards. In response, we have prepared a G-1 Issue Paper and are collaborating with the Federal Aviation Administration (FAA) to establish these standards.
Concurrently with the standards development process, we are formulating Means of Compliance (MoC) and Project Specific Certification Plans (PSCP). These conformity certification methods will guide us in conducting manufacturing of actual aircraft and undertaking a variety of ground and flight tests.
Our ultimate goal is to provide robust evidence that there are no safety concerns related to future HAPS large fixed-wing aircraft and to attain type certification.

Key point 3：CS-HAPS plays a pivotal role in enabling JARUS member countries to develop their own aviation regulations specifically tailored for HAPS operations.

In recent years, the Joint Authorities for Rulemaking on Unmanned Systems (JARUS) have undertaken areas that ICAO may not fully address. In response, international rulemaking efforts are currently in progress to establish standards pertaining to the airworthiness of unmanned aircraft. Recognizing the importance of this development, SoftBank actively engages in JARUS activities and is currently participating in the rulemaking process for CS-HAPS (Certification Specification for High Altitude Platform Systems) .

Key point 4：Implications of uncrewed aircraft and advanced air mobility rulemaking on HAPS

The development of international rules for unmanned aerial vehicles (drones) and flying cars is advancing more quickly than for HAPS and is proceeding globally. As there are some common elements with HAPS, it is also important to understand these trends. SoftBank has joined the Society of Japanese Aerospace Companies (SJAC). At the international committee level, SoftBank pays close attention to the global developments of ICAO/ICCAIA. In the Next Generation Air Mobility Study Committee, we follow the trends of public-private councils and the Realization of Advanced Air Mobility Project (ReAMO), as well as ISO/TC20/SC16, the specialized committee responsible for the international standardization of unmanned aerial vehicles, focusing on elements that could impact HAPS.

■Pilot Proficiency (License/Certification)

At present, pilots responsible for conducting test flights in the HAPS domain possess valid Pilot Licenses and have undergone specialized training specific to HAPS operations. In the future, we plan to participate in activities to establish a formal HAPS license.

■Rules of Air Operation

Key point：Active participation as an operator protects business development

Airspace regulations for operations above 60,000 ft/18 km differ across countries, leading to varied airspace designations. For instance, in the United States, airspace above this threshold is designated as "Upper Class-E." SoftBank is actively engaged in efforts to establish cooperative operating rules among operators in the higher airspace, both in the United States and globally.
To achieve this goal, we participate in key activities led by regulatory bodies such as the U.S. Federal Aviation Administration (FAA) and NASA. Specifically, we collaborate within the ETM (Upper Class E Traffic Management) Working Group and the m:n Working Group, foster partnerships across the aviation industry, and contribute to standardization efforts. As part of airspace management until the realization of ETM, the FAA's Central Altitude Reservation Function (CARF) proposes the use of Altitude Reservations (ALTRV), with plans to expand their application to include HAPS operations in the near future.

Furthermore, SoftBank, as a member of the private standardization organization RTCA (Radio Technical Commission for Aeronautics), actively participates in the development of performance requirements for unmanned aircraft systems through the Special Committee (SC) SC-228. We contribute our expertise to the development of Detect and Avoid (DAA) and Command and Control (C2) Link standards, including those specifically applicable to HAPS.

In Japan, HAPS large fixed-wing aircraft are categorized as Remotely Piloted Aircraft Systems (RPAS). We have communicated and engaged with the Japan Civil Aviation Bureau (JCAB) of the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) regarding the status of our efforts related to HAPS. JCAB is promoting environmental improvement for RPAS from the field of cargo transport. To further advance the environmental development and innovation of RPAS, SoftBank has been an active member of the Aviation Innovation Promotion Association-JAPAN RPAS Committee (AIDA-JRPAS) since its establishment in 2018. AIDA-JRPAS is a private organization that brings together experts in RPAS technology, operations, and legislation from industry, government, and academia. Through systematic discussions, leveraging the expertise of its members, AIDA-JRPAS addresses key issues and fosters collaboration to drive the safe and efficient integration of RPAS.
In addition to our involvement with AIDA-JRPAS, SoftBank is also a member of the Air Traffic Control Association of Japan (ATCA-J). Through our participation in ATCA-J, we engage in systematic discussions related to airspace management, flight methods suitable for safe HAPS operations, and the content of air traffic control. These discussions benefit from the insights and advice of air traffic control experts, ensuring that we consider and address all relevant aspects of HAPS operation.

Please also refer to "The Future of HAPS Fleet Operations Ensuring Flight Safety."

4. Future Prospects

Building on the collective efforts and achievements of countries, organizations, and companies, ICAO is currently engaged in the formulation of HAPS aviation rules. As a testament to this progress, SoftBank, as one of the founding initiators of the HAPS Alliance, had the honor of presenting a panel discussion on the concept and economic value of utilizing high-altitude airspace during the ICAO Air Navigation World event in August 2023.

In parallel, ICAO has introduced several notable initiatives related to HAPS:

- High-Level GAP analysis
- Launch of HAO Community website and invitation to authorities and stakeholders from various countries
- The publication of informative State Letters

These initiatives reflect the advancing phase of HAPS towards concrete implementation. On December 18, 2023, a significant joint statement was released by Japan, United States, United Kingdom, Canada, the European Union, and its member states. This statement urges the ICAO to actively promote the development of the rules for civil aircraft operations in higher airspace.

SoftBank remains deeply committed to actively participating in the standards development activities led by various countries and standardization organizations, as we work towards the commercialization of HAPS. While our aviation rule activities have been initiated by a small dedicated team, we recognize the vital importance of fostering world-class talent through certification and standardization activities.

Given the strategic significance of HAPS commercialization, SoftBank undertakes a leadership role in driving towards being the world's first and foremost in HAPS commercialization. As we continue to promote aviation rule activities and seek global competitiveness, we are dedicated to playing a pivotal role in shaping the future of HAPS technology and operations.