The global aviation industry, a pinnacle of modern engineering and safety, is built on a foundation of precision. For decades, Global Navigation Satellite Systems (GNSS), particularly the Global Positioning System (GPS), have been integral to this precision, enabling efficient routes, complex approaches, and enhanced situational awareness. However, this reliance has introduced a critical vulnerability. The OpsGroup report into GPS Spoofing published in September 2024 serves as a stark case study, documenting how the weaponization of GPS spoofing in regional conflicts has created a cascading safety crisis for civil aviation, exposing an urgent need for more resilient Position, Navigation, and Timing (PNT) systems.
GPS interference is not new, but the nature and scale of the threat have changed dramatically in recent years. The OpsGroup report highlights a staggering increase in jamming (the simple blocking of GPS signals) and spoofing (the transmission of false signals), growing from an average of 300 affected flights per day in early 2024 to 1,500 flights per day by August 2024. In the single month from mid-July to mid-August 2024, a total of 41,000 flights experienced spoofing.
There is no evidence yet to suggest that this is a targeted attack on civil aviation. The report clarifies that these incidents are most likely collateral damage from regional conflicts, where GPS jamming and spoofing is used to try to defend against attacks from drones and GPS-guided munitions. However these counterfeit signals are broadcast at much higher signal strengths than the true satellite signals, and so as aircraft fly near these conflict zones—primarily the Eastern Mediterranean, the Black Sea, and the India/Pakistan border—their receivers pick up these powerful, counterfeit signals from hundreds of kilometres away.
Pilots are trained to navigate without GPS, and it is still in general an advisory technology. The core of the spoofing challenge does not lie in the pilot’s navigation options, but rather lies in the impact that GPS spoofing has on other parts of the avionics on a modern airliner. The OpsGroup report reveals that in a typical spoofing attack 20-30 other systems can alarm, fault or suffer interference. When an aircraft's GPS receiver is deceived, it passes erroneous position, altitude, and time data to other systems. The impacts documented in the report include:
A particularly dangerous finding is the concept of a "contaminated" receiver. A GPS unit may appear to recover after leaving a spoofing area, but it can retain corrupted ephemeris (satellite orbital) data. This creates a latent vulnerability where the receiver could begin outputting erroneous data hours later, a scenario with grave implications for GPS-reliant RNP (Required Navigation Performance) approaches, especially in poor weather. In these instances the receiver needs to be fully reset (power cycled) in order to ensure that its memory has been cleared of all spoofed data.
The OpsGroup report makes it clear that there are no quick fixes. The industry's response must be multi-layered, focusing on both immediate mitigation and long-term solutions to build a more resilient PNT ecosystem. The report provides example guidance to pilots, adopting the same “prepare, act, recover” concept as the RIN Best Practice Guidelines for Resilient PNT. Aircraft manufacturers and airlines have been gradually rolling out their own specific guidance materials through 2025, and in some cases the “normal operating procedures” now include the use of the circuit breakers to reset systems in flight.
1. Crew Training and Awareness: Airlines must urgently train crews on how to recognize, manage, and recover from a spoofing. This includes simulator training for unusual scenarios like high-altitude go-arounds triggered by false EGPWS alerts.
2. Live Threat Mapping: Providing crews with up-to-date maps of active spoofing zones is one of the most effective tactical defenses, allowing them to prepare systems in advance.
3. In-Flight Resets: The report advocates for reviewing procedures to allow in-flight resets of GPS and EGPWS systems via circuit breakers, which can restore functionality after an event.
4. Controlled Reception Pattern Antennas (CRPA): Heavily favored by the workgroup, CRPAs are "smart" antennas that can identify the direction of an incoming signal and nullify interference from ground-based spoofers, focusing only on the legitimate signals from satellites above. Their adoption in civil aviation is seen as a critical step forward.
5. Improved Receiver Logic: Avionics manufacturers can update receiver software to include "gross error checks," making them more skeptical of sudden, large jumps in position or time after a signal loss.
6. System Isolation: A key architectural flaw is the inability to isolate the GPS receiver from critical systems like the EGPWS. Future designs must allow for this "quarantining" of a compromised data source.
7. Strengthening Alternatives: The crisis has highlighted the over-reliance on GPS in civil aviation’s systems engineering. A renewed commitment to maintaining and strengthening the network of ground-based navigation aids (e.g., VOR, DME) is essential to provide a reliable backup layer.