C H A P T E R

N ° 33

Modern vs. Autonomous Aircraft (Part 2)

Activities occurring on the Sun (i.e., solar activity) can create space weather influencing the performance and reliability of space-borne, air-borne, and ground-based technological systems. Additionally, in some instances, it can even endanger human life and health. The future indicates an ever-growing dependency on advanced technologies to enable a plethora of services and capabilities. This is especially within critical infrastructures like the aviation industry, which is on a trajectory to provide fully autonomous air vehicles (aircraft) in the future.

Some aircraft are already close to being semi-autonomous. Modern aircraft, particularly long-haul airliners, utilize semi-autonomous systems. These systems are used for much of the routine flight tasks, allowing pilots to focus on more complex aspects of flight and contingency management. While fully autonomous flights are still in development for commercial aircraft, the technology for semi-autonomous and even fully autonomous flight already exists. 

In Hoplon’ articles; C H A P T E R  N ° 27-31, we provide an introduction to the relation between space weather and the aviation industry, exploring the interaction between space weather and the Earth’s natural planetary defence systems, avionics, and aircrews. Additionally, we discuss the associated risks of financial losses caused by space weather impact and some of the currently available mitigation measures. Lastly, we discuss the effectiveness of radiation protection measures for aircrews and aircraft.

Today’s article is a continuation of C H A P T E R  N ° 33  Modern vs. Autonomous Aircraft (Part 2), and will be the third of four articles focused on exploring the topic of autonomous aircraft and how space weather may affect them. Throughout this mini-series, we will look closer at how autonomous aircraft are classified and how they work. Additionally, we will discuss the risks and vulnerabilities of such inventions starting by looking at how space weather interacts with the data transferring process from satellites to receivers on ground and in air, and how this can create complications for satellite-driven services focusing on autonomous aircraft. Moreover, we will look at specific space weather impacts on aircraft comparing modern and autonomous air vehicles, and provide examples. Lastly, we will look closer at some of the currently available mitigation measures and the complexity of mitigation measure for autonomous vehicles.

Image Credit: Student Circuit.

How Space Weather affects modern vs. autonomous aircraft

Space weather can significantly impact air vehicles directly and indirectly through its dependency on satellite services. These vulnerabilities will only increase with the creation of autonomous aircrafts, despite the level of automation. An increase in the vulnerability of the aircraft increases the risk of potential safety issues for autonomous aircraft operations. In modern aircraft, space weather can impact in following ways:

Navigation and the Global Navigation Satellite System (GNSS)

Space weather can cause ionospheric disturbances that can significantly impact navigation and Global Navigation Satellite System (GNSS), including the Global Positioning System (GPS), which are all crucial for autonomous aircraft. These disturbances can lead to signal scintillation, increased positioning errors, and complete signal loss, affecting the accuracy and reliability of navigation systems used in various applications.

Ionospheric scintillation happens when solar activities such as solar flares and space weather events like geomagnetic storms changes the composition of the ionosphere, creating irregularities in the electron density, which can scatter and deflect radio waves. These irregularities cause radio signals from Global Navigation Satellite System (GNSS) satellites to fluctuate in amplitude and phase as they pass through the ionosphere. This fluctuation can disrupt or degrade the performance of satellite-based systems, such as the Global Positioning System (GPS). This is especially in equatorial and polar regions.

* Scintillation is a small flash of visible or ultraviolet light emitted by fluorescence in a phosphor when struck by a charged particle or high-energy photon. *

During the ionospheric scintillation, the incoming particles can disrupt the tracking of Global Navigation Satellite System (GNSS) signals by receivers, consequently causing signal degradation. This can lead to reduced accuracy and increased positioning errors. In severe cases, it can even cause a complete loss of signal, making technology dependent navigation capabilities impossible. The increased positioning errors can sometimes be inaccurate by a factor of ten or more, compared to normal conditions.

Furthermore, ionospheric disturbances can additionally cause Global Navigation Satellite System (GNSS) timing errors, which is a significant concern for autonomous aircraft. Global Navigation Satellite System (GNSS) timing errors can lead to inaccurate positioning, increasing the risk of air vehicles diverging from their flight paths due to inconsistent flight guidance, potentially causing uncommanded turns or other erratic behavior increasing the risk of collisions, or other safety hazards.

Modern aviation increasingly relies on Global Navigation Satellite Systems (GNSS) for precision approaches and landings, and enhanced situational awareness. Degradation or loss of this service can have severe consequences, especially in complex or congested airspace, as it can lead to significant safety and operational issues.

In an autonomous air vehicle, where its systems heavily rely on the Global Navigation Satellite System (GNSS) for navigation, losing this system presents a major challenge. This is much more complex than that of modern aircraft.

Autonomous air vehicles are exposed to the same effects from space weather as modern aircraft. However, in modern aircraft, pilots have the ability to fly without Global Navigation Satellite Systems (GNSS) in case of an emergency. Generally, in modern aircraft, the air vehicle can always fall back on the pilot in case an avionic component does not work properly. This is, however, not necessarily an option in fully autonomous aircraft where it may only have a turn on and off button and nothing else. An issue with the Global Navigation Satellite Systems (GNSS) can lead to a loss of position accuracy, potentially causing the autonomous aircraft to deviate from its planned route, or even crash.

Communication

Space weather can significantly disrupt radio communication. These disruptions occur because space weather affects the ionosphere, enabling it to absorb and deflect radio waves consequently hindering the transmission of commands and data to and from an aircraft. This can lead to increased risk of radio blackouts, signal degradation, and interference/noise, particularly affecting high-frequency (HF) radio and satellite-based systems.

The disruption of the radio communication data transfer can potentially disrupt the communication between autonomous aircraft and ground control.

A loss of radio communication in autonomous aircraft is a critical situation that can lead to mid-air collisions if not addressed promptly. Backup communication systems and robust procedures are essential to mitigate the risks associated with communication failures in autonomous flight. 

Situational Awareness

A disruption of the Global Navigation Satellite System (GNSS) services or timing errors can affect other onboard systems that rely on accurate positioning and timing data, such as Automated Dependent Surveillance-Broadcast (ADS-B), terrain avoidance systems (TAWS), and wind shear detection.

The Automatic Dependent Surveillance-Broadcast (ADS-B) is a surveillance technology that allows aircraft to determine their position using satellite navigation, and broadcast that information, along with other data, to other aircraft and ground stations. This broadcast enables air traffic control to track aircraft with greater accuracy and allows pilots to see a more detailed picture of the surrounding air traffic. A disruption of the Automatic Dependent Surveillance-Broadcast (ADS-B) can limit the situational awareness of both pilots (within semi-autonomous aircraft) and air traffic control, potentially increases safety risks. 

An inaccuracy within the Terrain Avoidance and Warning System (TAWS) or the wind shear detection could, similarly, lead to a loss of situational awareness, increasing the risk of accidents. A Terrain Avoidance and Warning System (TAWS) is an aircraft safety system designed to prevent Controlled Flight Into Terrain (CFIT) accidents. The Terrain Avoidance and Warning System (TAWS) provides both visual and aural alerts when the aircraft is in dangerous proximity to terrain or obstacles. This system enhances situational awareness and helps avoid potential collisions with the ground. In addition, aircraft utilize systems to detect wind shear, a change in wind speed or direction over a short distance, which can be hazardous during takeoff and landing. These systems are either reactive, responding to wind shear encountered by the aircraft, or predictive, alerting pilots, or the ground control in case of fully autonomous aircraft, to wind shear ahead.

Sensors and Control System

High-energy particles from solar activities causing space weather events can damage sensors and control systems onboard aircraft through various mechanisms. This can lead to aircraft malfunctions, such as disruption to navigation systems, communication failures, and increased radiation exposure on equipment and passengers. These malfunctions arise from the interaction of charged particles and electromagnetic radiation with Earth's magnetosphere and atmosphere.

Furthermore, the changes in Earth’s magnetic field caused by solar activity can affect magnetic-based equipment onboard aircraft. This can lead to inaccurate readings, increasing the risk of incorrect altitude indications, compass deviations, and unreliable fuel level readings, consequently increasing flight safety.

These effects are mainly when focusing on the impact from space weather on satellites. Additional effects and concern may arise through the impact of space weather on the energy sector and other terrestrial critical infrastructures that the aviation industry relies on for the well-functioning and safety of aircraft operations. 

These space weather effects are the same for autonomous air vehicles. However, every time a new technology and system is introduced and implemented in order to enable fully autonomous aircraft, the vulnerabilities and risks relating to space weather impact increases. This is due to the risks and vulnerabilities of technological systems to space weather effects.

Image Credit: OneLap: Cartoon showing how the Global Positioning System (GPS) works.

The February and May 2024 Space Weather events

In February 2024, a series of strong solar flares, including an X6.3 solar flares, impacted aviation by disrupting radio communications and navigation systems, like Automated Dependent Surveillance-Broadcast (ADS-B). Deviations in Automated Dependent Surveillance-Broadcast (ADS-B) reported positions showed to be correlating with the solar flare peaks and ionospheric disturbances mid-February. This was an experiences example of space weather impact on avionics, and highlighted the risks and vulnerabilities within aircraft tracking and situational awareness.

In May 2024, a geomagnetic storm occurred, later named ‘Gannon Storm’, which significantly impacted avionics systems, causing disruptions to Global Navigation Satellite System (GNSS) navigation, high-frequency (HF) radio communications, and potentially affecting aircraft tracking and situational awareness. Specifically, the space weather event led to fluctuations in ionospheric electron content, impacting Wide Area Augmentation System (WAAS) performance and causing communication anomalies, including high-frequency (HF) radio blackouts.

* Wide Area Augmentation System is a satellite-based augmentation system that enhances the accuracy, integrity, and availability of GPS signals, providing more precise navigation for aircraft. WAAS enables pilots to perform precision approaches, including Localizer Performance with Vertical guidance (LPV) approaches, which were previously limited to airports with ground-based navigation aids. *

The Global Navigation Satellite System (GNSS) was disrupted and was unreliable, consequently affecting the aircraft navigation systems that relied on the signals. This was all due to strong ionospheric gradients caused by the geomagnetic storm. Following the Global Navigation Satellite System (GNSS) disruptions, the Wide Area Augmentation System (WAAS) experienced loss of Localized Performance with Vertical Guidance (LPV), affecting operations at thousands of airports as it is crucial for precision approaches (i.e., landing).

Furthermore, the intense ionization from the solar flares during the May 2024 space weather event resulted in high-frequency (HF) radio blackouts, particularly affecting long-distance communication, including flight routes between the US and Europe. Routes flying over Greenland and Canada also experienced communications anomalies.

The February and May space weather events in 2024 are both testimonies of the potential risks and vulnerabilities within the aviation industry when it comes to space weather impact. These vulnerabilities will increase with fully autonomous air vehicles if proper research, and the investment in the creation and implementation of mitigation measures and strategies are not made.

Image Credit: NASA/SDO: NASA’s Solar Dynamics Observatory captured this image of a solar flare on 10 May 2024.

Image Credit:  Christian Harris: Aurora looking west in Utica, OH the night of the 10’th.

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