From GNSS dependence to navigation resilience: Why Aviation needs a new approach

For many years, Global Navigation Satellite Systems (GNSS) have been viewed as a critical enabler of modern aviation. They underpin Performance Based Navigation (PBN), Required Navigation Performance (RNP), ADS-B surveillance, Electronic Flight Bags, fleet tracking, airport surface operations and a growing range of digital aviation services. But recent events have exposed an uncomfortable reality:

GNSS is no longer just a navigation aid. It has become a critical dependency across the entire aviation ecosystem.

As interference incidents continue to increase across Europe, the Middle East and other regions, the industry faces a fundamental challenge. The question is no longer whether GNSS interference will occur. The question is whether aviation organisations can continue to operate safely and efficiently when navigation data can no longer be trusted.

GNSS interference has become an operational issue

For many years, GNSS jamming and spoofing were treated as technical anomalies or isolated regional issues. That assumption is becoming increasingly difficult to sustain. Recent incidents have demonstrated that GNSS disruption can affect aircraft operating hundreds of miles from conflict zones and can occur during all phases of flight. One widely reported example documented by a pilot involved an aircraft operating in the Jeddah Flight Information Region. During cruise flight at 37,000 feet, the aircraft experienced GNSS spoofing effects severe enough to generate anomalous terrain indications and false warnings within onboard systems. Although the aircraft remained controllable, crew workload increased significantly as pilots were forced to cross-check navigation information and revert to alternative navigation sources.

This highlights an important point:

The operational impact of GNSS disruption is not limited to loss of position information. The effects can propagate through multiple aircraft systems, influencing terrain awareness, navigation displays, surveillance functions and decision-making processes.

The result is increased uncertainty at precisely the moment crews and controllers require confidence.

A systemic risk, not a single-system failure

The aviation industry's challenge stems from the extent to which GNSS now supports critical operational functions.

GNSS contributes to:

• Flight management systems
• Precision navigation and approach procedures
• ADS-B surveillance
• Terrain awareness systems
• Autopilot and flight director’s functions
• Fleet management and operational control systems
• Airport surface movement operations
• Time synchronisation across aviation networks

When GNSS is degraded, the consequences extend far beyond navigation.

Disruption can cascade across multiple interconnected systems, reducing situational awareness, increasing workload and affecting operational efficiency across airlines, ANSPs and airports simultaneously.

This is why many regulators and industry bodies are increasingly describing GNSS interference as an aviation resilience challenge rather than a navigation problem.

The industry response Is evolving

Across the aviation sector, organisations are beginning to shift from incident management to resilience planning. Recent initiatives from ICAO, EASA, EUROCONTROL, IATA and national regulators have focused on:

• Enhanced pilot procedures for spoofing and jamming events
• Improved reporting and operational coordination
• Greater awareness of GNSS dependencies
• Assessment of precision approach resilience
• Strengthening national monitoring capabilities
• Development of alternative navigation strategies

These initiatives represent important progress.

However, procedures alone do not solve the problem. To make informed operational decisions, aviation stakeholders need a better understanding of what is happening in the radio-frequency environment in real time.

The missing piece: Persistent navigation trust awareness

Historically, aviation has relied heavily on pilot reports and aircraft observations to identify GNSS interference. While valuable, this approach is inherently reactive. By the time interference is reported, operational impacts may already be occurring. A more resilient future requires persistent awareness of the RF environment and objective measures of navigation trust.

This is where our recent work with CGI SignalSense provides a different approach. CGI SignalSense continuously monitors GNSS signals across distributed sensor networks, providing real-time awareness of interference activity, trends and hotspots. Rather than relying solely on aircraft reports, organisations gain:

• Continuous monitoring of GNSS performance in real-time to detailed granularity understanding the frequency, strength and risk to aircraft based on their onboard GNSS receivers
• Detection of jamming and spoofing activity
• Identification of wide-area interference events
• Historical trend analysis
• Regional risk assessments
• Objective severity measurements

For airlines, drone operators and ship operators this can support route risk assessment and operational planning.

For ANSPs, it can provide enhanced situational awareness of airspace conditions.

For airports, it offers improved understanding of local vulnerabilities affecting precision navigation and surface operations.

The goal is simple:

Enable organisations to understand not only where interference occurs, but how much operational confidence can be placed in navigation services at any given time.

Beyond detection: What happens when GNSS cannot be trusted?

Awareness alone is not enough. Eventually, aviation must answer a more difficult question:

What happens when GNSS becomes unavailable or untrusted?

This is where Alternative Positioning, Navigation and Timing (Alt-PNT) capabilities become increasingly important. The future of resilient aviation operations will likely involve multiple complementary sources of navigation and timing information rather than dependence on a single technology. Potential sources include:

• High-performance inertial navigation
• DME and conventional navigation aids
• Terrain and map matching
• Multilateration
• Hybrid sensor fusion
• Low Earth Orbit (LEO) satellite-based positioning systems

By combining these sources, aviation operators can maintain continuity even when GNSS performance degrades.

CGI Alt-PNT: Building resilience beyond GNSS

CGI's Alt-PNT capability is designed to provide resilient Positioning, Navigation and Timing independent of traditional GNSS signals.

Using authenticated LEO satellite signals, the approach offers:

• Resistance to spoofing attacks
• Significantly stronger signal power than traditional GNSS
• Global coverage
• High-accuracy positioning and timing
• Support for operations in contested electromagnetic environments

Most importantly, Alt-PNT enables continuity of operations when GNSS becomes degraded, denied or untrusted.

For aviation stakeholders, this means resilience becomes proactive rather than reactive.

The future is navigation trust management

The aviation industry's challenge is no longer simply providing navigation. It is continuously assessing whether navigation information can be trusted.

Future aviation resilience will likely depend on four interconnected capabilities:

1. Persistent awareness of the RF environment
2. Real-time assessment of navigation trust
3. Access to resilient alternative navigation sources
4. Operational decision-making informed by both

This represents a shift from GNSS dependence towards navigation trust management.

Organisations that can detect interference, understand its operational impact and maintain alternative sources of Positioning, Navigation and Timing will be better positioned to maintain safety, efficiency and service continuity in an increasingly contested environment.

The future of resilient aviation is not about replacing GNSS. It is about ensuring that when GNSS cannot be trusted, operations can continue with confidence. For more information regarding CGI in Aerospace, click the link below.

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