High-altitude pseudo-satellite systems (HAPS) represent a transformative class of unmanned platforms designed to operate in the stratosphere, typically between 18 and 50 kilometers above sea level. By combining the endurance of satellites with the flexibility of aerial vehicles, these systems promise persistent coverage for communications, earth observation, disaster management, and defense applications. However, bringing a HAPS platform from concept to operational deployment demands meticulous navigation of a multilayered regulatory framework spanning aviation, telecommunications, environmental protection, and international law. This article provides a comprehensive guide to the regulatory landscape for HAPS, offering actionable insights for developers, operators, and policymakers.

Foundations of HAPS Regulation

Defining HAPS in International Law

The term “high-altitude pseudo-satellite” does not yet have a universally binding legal definition, but several international bodies have made progress toward classification. The International Telecommunication Union (ITU) defines HAPS as “a station on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the Earth.” This definition is crucial for frequency allocation and orbital slot coordination. The International Civil Aviation Organization (ICAO) treats HAPS as unmanned aircraft systems (UAS) when they are capable of sustained flight, bringing them under the umbrella of the Chicago Convention and its annexes. The overlap between aviation law and telecommunications law is where most regulatory complexity arises.

Key International Bodies and Their Roles

Navigating HAPS regulation requires engagement with at least four categories of authorities:

  • Telecommunications regulators: The ITU and national bodies such as the Federal Communications Commission (FCC) in the U.S. and the European Communications Office (ECO) manage spectrum licensing and interference mitigation.
  • Aviation authorities: ICAO establishes global standards for airworthiness, pilot licensing (even for remotely piloted systems), and air traffic management. National aviation authorities (e.g., FAA, EASA) implement these standards.
  • Space agencies: For HAPS platforms that operate in the upper stratosphere and may be considered “near-space” vehicles, coordination with space agencies becomes important for orbital debris mitigation and remote sensing licensing.
  • Environmental and safety regulators: Agencies like the U.S. Environmental Protection Agency (EPA) or the European Environment Agency (EEA) may require environmental impact assessments, especially for long-duration flights that could affect the stratospheric ozone layer or wildlife.

Spectrum Allocation and Frequency Licensing

The ITU has dedicated significant effort to HAPS spectrum through Recommendation ITU-R M.2201, which identifies frequency bands suitable for HAPS communications links. Primary candidate bands include portions of the 31/28 GHz range (Ka-band) and the 47.2–48.2 GHz range (V-band). However, these bands are also used by fixed satellite services and terrestrial fixed links, making coexistence studies essential. Operators must submit detailed interference analyses to their national spectrum administration, who in turn coordinate with the ITU Radiocommunication Bureau to update the Master International Frequency Register.

National Spectrum Licensing Challenges

Securing a spectrum license for HAPS is rarely a straightforward process. Many national regulators have not yet updated their frequency allocation tables to include a specific “HAPS” service category. Developers often need to apply under experimental or temporary licenses during testing phases, then transition to a full commercial license as regulations evolve. For instance, in the United States, the FCC adopted a Report and Order in 2023 that created a new service category for HAPS in the 2.5 GHz band for broadband operations, but only after several years of industry advocacy and technical demonstrations. The European Conference of Postal and Telecommunications Administrations (CEPT) has developed ECC Recommendation (20)02 to harmonize HAPS spectrum across Europe, but adoption varies by member state.

Cross-Border Coordination

Because HAPS platforms can loiter over international waters or straddle national airspace boundaries, spectrum coordination with neighboring countries is mandatory. The ITU provides mechanisms for bilateral and multilateral agreements, but operators must be prepared for lengthy negotiation cycles. A best practice is to submit a Notice of Intent to the ITU at least 18 months before planned deployment, as outlined in Article 9 of the ITU Radio Regulations.

Airspace Integration and Aviation Safety

Classifying HAPS for Air Traffic Management

HAPS platforms operate in a part of the atmosphere that is technically airspace subject to national sovereignty, but above the altitudes typically used by commercial aviation (up to FL 600). This “upper airspace” or stratospheric airspace is still managed by civil aviation authorities. ICAO has developed the concept of “Remotely Piloted Aircraft Systems (RPAS)” which applies to HAPS that are controlled from the ground. Under ICAO Annex 2 and Annex 8, HAPS must comply with airworthiness certification requirements tailored to their unique operating environment. In practice, many national authorities grant HAPS a special “high-altitude operation” certificate that combines elements of manned aircraft certification (e.g., structural integrity, emergency systems) with UAS-specific rules (e.g., command and control link integrity, lost link procedures).

Detect and Avoid (DAA) Systems

Given the thin air density and high speeds at stratospheric altitudes, conventional aviation surveillance radars have limited effectiveness. HAPS must therefore be equipped with electronic conspicuity systems (e.g., ADS-B Out at extended ranges) and sophisticated detect-and-avoid algorithms that can handle non-cooperative targets like weather balloons or amateur rockets. The FAA has published Advisory Circular AC 90-XX (in development) specifically for high-altitude operations, while EASA’s “Special Condition for High-Altitude Platform Stations” includes DAA performance requirements. Developers should budget for extensive flight testing to validate these systems in the operational envelope.

Launch and Recovery Airspace

One of the most critical regulatory hurdles is the airspace required for launch and recovery. HAPS platforms are often launched from ground sites at low altitudes (similar to general aviation airports) and must transition through busy terminal airspace to reach the stratosphere. This necessitates Temporary Flight Restrictions (TFRs) and close coordination with air traffic control. Some operators have chosen to launch from remote locations or offshore platforms to minimize conflicts.

Environmental and Safety Regulations

Stratospheric Impact Assessments

The stratosphere is a fragile layer that protects life on Earth from ultraviolet radiation. HAPS platforms, particularly those propelled by solar-electric power, have a relatively low environmental footprint compared to conventional aircraft, but they still pose risks. National environmental agencies may require an Environmental Impact Statement (EIS) that covers: potential ozone-depleting emissions from any backup chemical propulsion systems, electromagnetic interference with weather balloons and scientific instruments, and the effect of operations on migratory bird routes at high altitudes. In the European Union, the Strategic Environmental Assessment (SEA) Directive (2001/42/EC) applies to plans and programs that set the framework for projects like HAPS networks. Operators should commission independent studies early and present them to regulators alongside the permit application.

Battery and Solar Panel Disposal

End-of-life considerations are also subject to regulation. Many HAPS designs use lithium-ion batteries that pose fire and toxic waste risks. Disposal plans must comply with the Basel Convention on hazardous waste shipments, even for platforms that eventually fall into international waters. The International Maritime Organization’s London Protocol prohibits dumping of waste at sea, so recovery plans must ensure the platform is brought back to a licensed facility.

Safety Certification for Long-Duration Flight

HAPS platforms may remain aloft for weeks or months, far exceeding typical UAS endurance. Safety certification must address structural fatigue due to thermal cycling (temperatures can drop to -70°C at altitude), icing in the lower stratosphere, and the reliability of solar arrays and battery systems over extended periods. The FAA’s type certification process for special classes of aircraft (14 CFR Part 21.17(b)) allows for unique means of compliance, but developers should expect multiple rounds of review and test flights before receiving a Type Certificate.

International Law and Treaty Obligations

Outer Space Treaty Considerations

While HAPS do not reach orbital space (above 100 km under the Fédération Aéronautique Internationale definition), some so-called “near-space” operations may raise questions under the Outer Space Treaty of 1967. For instance, if a HAPS platform carries a payload that could be considered a “space object” (such as a high-resolution camera with a large footprint), it may be subject to Article VI responsibility for national activities. The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) has not yet issued definitive guidance, but prudent operators register their platforms with national space agencies to avoid ambiguity.

Telecommunications and Broadcasting Treaties

Beyond spectrum coordination, HAPS that provide broadcasting services must comply with conventions such as the 1985 ITU Broadcasting-Satellite Service (BSS) rules. If a HAPS platform relays signals across borders, it may trigger obligations under the World Trade Organization’s Basic Telecommunications Agreement (BTA) regarding market access and universal service. Operators should work with legal experts familiar with both telecom law and trade law to secure the necessary authorizations.

Case Studies in Regulatory Navigation

Project Loon (Alphabet/Google)

Project Loon, which operated high-altitude balloons (not propelled aircraft, but often compared to HAPS), deployed in several countries including Puerto Rico, Peru, and Kenya. The project demonstrated the importance of early engagement with telecom regulators. In Kenya, Alphabet worked closely with the Communications Authority to secure experimental licenses and later a commercial spectrum agreement. However, the project also faced airspace conflicts with aviation authorities, leading to temporary suspensions. The key lesson: proactively involve both the telecommunications and aviation regulator simultaneously, not sequentially.

Airbus Zephyr

Airbus’s Zephyr series, a solar-powered HAPS aircraft, received an experimental airworthiness certificate from the UK Civil Aviation Authority (CAA) in 2020 for test flights. The CAA adapted its existing UAS regulations (CAP 722B) to cover the Zephyr’s unique altitude capability, requiring Airbus to demonstrate a “safe descent” profile in case of engine failure. Airbus also secured an ITU filing for a 2.5 GHz spectrum allocation for its trials. The Zephyr experience shows that a combination of transparent safety documentation and willingness to accept operational restrictions (e.g., flight only over designated danger areas) can accelerate approval.

SoftBank HAPS (HAPSMobile)

SoftBank’s HAPSMobile (now AeroVironment) collaborated with the Japanese Ministry of Internal Affairs and Communications to create a national HAPS regulatory framework. Japan’s “Basic Plan for the Development of High-Altitude Platform Stations” (2021) set out a roadmap for spectrum allocation, airspace integration, and safety standards. This case underscores the value of participating in rulemaking processes rather than waiting for regulations to emerge. SoftBank also engaged with the ICAO’s RPAS Panel to influence global standards.

Best Practices for a Streamlined Regulatory Path

Develop a Regulatory Roadmap Early

Begin by mapping all required permits, certifications, and consultations across jurisdictions. Create a timeline that accounts for the 12–24 months typically needed for spectrum coordination and airspace integration approval. Include milestones such as pre-application meetings, draft EIS submissions, and test flight authorization.

Leverage Multilateral Forums

Participate in ITU-R Study Group 3 (radiowave propagation) and Working Party 5C (fixed wireless systems) to influence HAPS spectrum standards. Join ICAO’s RPAS Panel and the Future Air Navigation Systems (FANS) committee. These forums provide early insight into regulatory changes and allow developers to submit technical data that shapes the rules.

Conduct Parallel Safety and Environmental Studies

Rather than waiting for regulators to request studies, proactively commission an independent safety assessment (e.g., System Safety Assessment per SAE ARP4761) and an environmental impact report. Deliver these documents with the initial permit application to demonstrate due diligence.

Build a Compliance Management System

Regulatory compliance does not end at launch. Operators must maintain logs of radio frequency usage, air traffic control communications, and environmental monitoring. Implement a digital compliance platform that can generate reports on demand for audit by national authorities. The EASA “Regulation (EU) 2019/947” for UAS operations includes requirements for remote identification and geo-awareness, which HAPS operators can extend into the stratosphere.

The Future Evolution of HAPS Regulation

Harmonization Efforts Under ICAO and ITU

Both ICAO and the ITU are working toward harmonized global HAPS regulations. ICAO’s High-level Conference on Aviation and Alternative Fuels (CAAF) has included HAPS as a topic for future standards, and the ITU’s World Radiocommunication Conference (WRC-27) agenda includes agenda item 1.13 specifically for HAPS. By 2027, a more coherent international framework is expected, which should reduce the patchwork of national rules.

Regulatory Sandboxes and Pilots

Several countries, including Singapore, the United Arab Emirates, and Finland, have established “regulatory sandboxes” for HAPS. These allow operators to test systems under relaxed rules with oversight. The data gathered feeds into permanent rulemaking. Developers should prioritise sandbox applications as a low-risk entry point.

Autonomous Operations and Spectrum Sharing

Advances in autonomous flight control and dynamic spectrum sharing (like Licensed Shared Access) will require regulatory updates. The FCC has proposed rules for “frequency agile” HAPS that can shift bands to avoid interference. Future regulations will likely mandate AI-driven spectrum coordination between multiple HAPS constellations and terrestrial networks.

Conclusion

The regulatory landscape for high-altitude pseudo-satellite systems is complex but navigable with a strategic, proactive approach. Successful operators combine deep technical knowledge of stratospheric operations with a thorough understanding of telecommunications, aviation, and environmental law. By engaging early with international bodies, producing rigorous safety and environmental documentation, and participating in rulemaking processes, developers can overcome the current fragmentation and unlock the full potential of HAPS for global connectivity and observation. As WRC-27 and ICAO’s next standards cycle approach, the window is open for industry to shape a framework that is both safety-conscious and innovation-friendly.