Airports are built on precision.
Each aircraft’s takeoff, landing, and movement on the ground depend on several systems that have to function almost flawlessly together. These systems include navigation, surveillance, time, and communication, all of which require accurate data around the clock.
What, however, will happen if GNSS breaks down? The repercussions will definitely go beyond just the flight deck to encompass the entire airport as well.

A Hidden Layer of Dependency
GNSS is commonly associated with airborne navigation, guiding aircraft across continents and through complex approach procedures. But its role on the ground is just as critical.
Airport operations depend on GNSS for:

• Precision approach and landing systems
• Surface movement tracking and surveillance
• Time synchronisation across communications and IT networks
• Ground operations coordination
• Most of the above-mentioned systems function without much ado, hence the importance of the role played by GNSS is often forgotten.
• Until something breaks down.
• When One Signal Becomes a Systemic Risk

Although isolated failures in the machine are unlikely to cause any harm to numerous functions, GNSS disruption may possibly affect various systems at once.
Interference with the system’s functioning, regardless of the type, can lead to inconsistent performance in navigation, synchronisation, and surveillance functions.
Flight positioning data may be compromised. The synchronisation process may become faulty. Information provided by surveillance tools may contradict.
Individually, each of the mentioned aspects is a problem on its own. Yet when combined, it brings about yet another level of difficulty. This does not necessarily lead to complete paralysis of operations, but creates doubts about the efficiency of systems ensuring the airport’s efficient functioning.

A Real-World Glimpse of the Risk
Recent events have confirmed that GNSS’s impact is not limited to flights alone. Even airport operations have experienced disturbances as a result of GNSS interference. It was found that in some regions in Europe and the Middle East, the long-term disruption to GNSS service did not affect just the GNSS system’s ability to transmit location information to the planes, but even interfered with equipment used in ground systems employing synchronised timekeeping technology.
In addition, it was pointed out that pilots had difficulty navigating when approaching the airport as well as with surveillance data, which monitors the aircraft’s ground movements.

The Role of Timing in Airport Operations
Another important yet often overlooked area where GNSS plays a significant role is timekeeping.
Timing accuracy in airports is highly important for communication and networking operations. While minor problems in the GNSS clock may not lead to system failure, they can create a misalignment problem.
This will lead to the inability of the systems to operate in harmony, resulting in delays and more work for the operators and people on the ground. Isn’t that inconvenient?

Building Resilience Into the System
Mitigation strategies for disrupting GNSS signals need to be addressed from an entirely different angle. As opposed to depending on GNSS signals, the new approach involves planning for instances where these signals could fail or be disrupted. This would involve:

• Introducing backup timing resources to ensure synchronisation
• Improving monitoring mechanisms to detect problems as soon as possible
• Implementing a multilayered navigation approach that will not overly depend on one signal
  Preparing plans for operation with degraded GNSS signals
• Among other technology companies operating in the aerospace and defence industries, Safran has been instrumental in helping develop technology that can enhance signal validation and timing accuracy in the midst of GNSS disruptions.

From Efficiency to Assurance
For years, GNSS has enabled airports to operate more efficiently, supporting optimised routing, reduced separation, and streamlined ground operations.
In any case, the spotlight is moving.
Efficiency is still of utmost importance, but now resilience is equally necessary. It is not enough for the system to work efficiently if everything works properly. Rather, it should function even under conditions of stress.
To achieve such results, a wider and more holistic approach is needed.

An Overlooked Vulnerability
GNSS disruption is often discussed in the context of aircraft navigation. However, its impact on airport operations remains less widely understood.
Yet the risk is clear.
When a single signal supports multiple systems, its failure can have far-reaching consequences. Not necessarily catastrophic, but complex, cascading, and difficult to manage in real time.

Rethinking the Foundation
Airports will continue to rely on GNSS as its capabilities are too valuable to replace. However, there must be a balance between dependency and resilience.
Because in a world where signals may be interfered with, compromised, and manipulated, efficiency in airport operations alone will not suffice as the basis of strength. Rather, it lies in their ability to remain resilient despite the uncertainty within their dependent systems.
When there is one failed signal, it will no longer be a matter of whether airport operations can go on, but how prepared the entire system is for other signals to go out of the way.