AMC1 NCC.OP.153 relates to the European Union Aviation Safety Agency (EASA) regulations for non-commercial operations of complex motor-powered aircraft (NCC). Specifically, this part of the regulations addresses the operational procedures and equipment requirements to ensure safety and compliance.

When the regulation asks for a demonstration that the GNSS (Global Navigation Satellite System) is “robust against loss of capability,” it is asking for evidence that the system can continue to operate effectively even if some aspects of its functionality are degraded or lost. In the context of GNSS, robustness refers to the system’s ability to withstand or recover from conditions that could impair its accuracy, availability, and reliability. These conditions include spoofing (where false GNSS signals are sent to mislead the receiver) and jamming (where GNSS signals are intentionally interfered with to prevent their reception).

The term “robustness” in this context applies primarily to the aircraft’s GNSS equipment and its ability to handle such adverse conditions. It is about how the aircraft systems that rely on GNSS for navigation and timing can maintain their functionality in the face of potential threats to GNSS signal integrity.

Qualifying the robustness of GNSS in aircraft systems involves:

Testing and Evaluation:
Aircraft systems are subjected to various scenarios that simulate GNSS signal degradation, including both spoofing and jamming. The aim is to evaluate how the system detects and mitigates these threats.

Redundancy:
Ensuring that there are backup systems or methods in place if GNSS data becomes unreliable. This could include alternative navigation systems like INS (Inertial Navigation Systems) or the use of other satellite constellations.

Fail-safe Mechanisms:
Implementing procedures and technologies that allow the aircraft to maintain a safe state or transition to one in the event of GNSS failure.

Detection and Mitigation Techniques:
Incorporating technologies that can detect spoofing or jamming attempts and either correct for them or alert the crew to switch to alternative navigation methods.

In essence, the demonstration of robustness against loss of GNSS capability is a multifaceted process. It involves proving that the aircraft’s systems can identify when the GNSS signals are compromised and either correct for this or employ alternative measures to maintain navigational accuracy and safety.

Hey Benjamin, thanks for clarification - that helps a lot. The question is now, how can an operator get to know these complex technical requirements and is there an awareness present about the systems capabilities. What can be expected from a common user, how does training cover these topics...it is far from being trivial?