Technical Elements for Safety of HAPS Navigation

SoftBank is developing various technologies to provide communication services from stratospheric platforms (HAPS). In this article, we will explain the technical elements that support safety of HAPS navigation.

The elements that support the safety of HAPS navigation can be broadly divided into three categories: "aircraft systems," "pilots," and "flight control”. Flight control here refers to the monitoring of navigation conditions, replacement of aircraft, and reassignment of aircraft when problems occur. In order to continuously provide the communication services, it is important for communication service providers themselves to proactively perform flight control and ensure the safety of HAPS operations as a whole.

Challenges in HAPS Flight Control

A typical passenger aircraft is operated with one or more pilots on board for flight durations of 24 hours or less. In contrast, HAPS is operated remotely, with the pilot on the ground for long periods of time, as long as several months. The goal is to achieve M:N operations, in which a small number of pilots manage a large number of aircrafts from the standpoint of business feasibility. Furthermore, during ascent and descent into the stratosphere, the aircraft must operate through airspace where jet aircrafts frequently pass by.

Various perspectives need to be considered for flight control, and we will discuss the issues from each of the following four main perspectives.

①Airspace Monitoring

Ensure safe separation distances from drones, VFR (Visual Flight Rules) aircraft, aircraft under air traffic control, business jets, etc.

②Flight Planning and Management

Prediction and optimization of operational plans taking weather and energy balance into consideration

③Stratospheric Air Traffic Control

Adaptation to an architecture in which service providers using the stratosphere cooperate and share operational data

④Aviation Regulation Development/Adaptation

Developing standards for obtaining business licenses from the authorities to conduct surveillance and remote piloting, etc.

Steps for HAPS Operations

In order to resolve these issues, we must steadily step up our overall operations to achieve the operational vision for the service expansion period.

Therefore, we will start by establishing an operation in which a single pilot navigates a single aircraft while monitoring its flight status in a wide airspace. After that, we will conduct research and development to enable more challenging operations, such as M:N monitoring, coordination with air traffic control agencies, and simulation-based forecasting and optimization of flight plans, in order to further improve the efficiency of flight operation control.

• * FIR：Airspace where various types of information necessary for aircraft navigation and search and rescue operations are conducted so that the smooth and safe flow of air traffic in the world's skies can be facilitated.
• ** C2 Link：Command-and-control communication for HAPS piloting

Research and Development of HAPS Air Traffic Management

SoftBank currently has a joint research agreement with the Electronic Navigation Research Institute of the National Maritime, Port and Aviation Research Institute (hereinafter referred to as "ENRI"), in the field of air traffic management for HAPS.

Before HAPS can ascend into the stratosphere, it must pass through airspace that is traversed by a wide range of existing air traffic.
In order to ensure the safety of HAPS navigation and ensure the level of service while being compatible with existing air traffic, it is extremely important to select the airspace in which to design the flight plan.

Based on the HAPS aircraft specification data and weather data that SoftBank has accumulated through its past demonstrations, flight simulations are performed to calculate the necessary airspace for navigation. Furthermore, the existing air traffic environment, which has various characteristics depending on the season, time of day, altitude zone, etc., is simulated to calculate the candidate airspace that can provide the necessary area for navigation, making it possible to create the optimal flight plan.

Thus, by combining SoftBank's HAPS expertise with ENRI's analytical capabilities in the field of air traffic management, we will be able to solve HAPS issues in this field.

In addition to communication services, HAPS is expected to be utilized for monitoring terrestrial conditions in cases of disasters and for environmental monitoring in the future. SoftBank, as the driving force behind the HAPS project, will continue to promote research and development of flight control technology, taking a leading role in securing the safety of HAPS flights.