The European MON complements the CNS Evolution Plan, a key deliverable of the CNS PM. It is part of the contingency measures required by regulation (EU) 2017/373 to mitigate the risk of ATS disruption. It ensures that ATM/ANS providers can continue services through alternative means if GNSS or other navigation methods fail, enhancing CNS infrastructure resilience. The CNS MON also supports cost and spectrum efficiency, as well as environmental sustainability. Its scope depends on the severity and likelihood of identified risks and may not guarantee full business continuity or capacity in all situations.
Minimum Operating Network Concept and Design Criteria

This document is a product of the Communication Navigation and Surveillance Programme Manager (CNS PM), a task undertaken by EUROCONTROL in its role as Network Manager (NM) in full partnership with all relevant stakeholders.
The document defines the concept of a European civil CNS Minimum Operational Network (MON), aimed at enhancing the cost-effectiveness of the CNS infrastructure through optimisation. This includes the decommissioning of certain communications, navigation and surveillance assets, while ensuring adequate resilience and maintaining acceptable levels of safety and security. It also provides design criteria for developing such a CNS MON.
Context
In the event of CNS degradations, the infrastructure must remain safe, robust, and resilient. This requires thorough evaluation of reversion and contingency scenarios to ensure target performance levels.
The term MON has traditionally been associated with the minimum navigation infrastructure that allows aircraft to revert to conventional navigation procedures after a loss of Global Navigation Satellite System (GNSS) service. This document extends the MON concept to CNS, considering both the minimum infrastructure needed for seamless operations and contingency procedures.
Iterative Evolution Process
The European MON design establishes a baseline framework to ensure a safe and secure contingency service, while recognising the dynamic nature of air traffic management and diverse airspace user needs. The design will evolve iteratively through a structured process involving:
- Initial European MON Design: Establishing the foundational framework.
- National MON Assessment: Designated ANSPs, in cooperation with State Authorities, will assess and adapt the MON to meet specific operational needs and local conditions.
- Feedback Mechanisms: Utilising existing tools (e.g. LSSIP) to gather stakeholder feedback for ongoing refinements.
- Continuous Improvement: The MON will continuously improve based on feedback, emerging technologies, regulatory updates, and evolving operational requirements, including accommodating new entrants.
This iterative approach contributes to the development of a realistic European CNS Evolution Plan.
Document structure
The EU MON document comprises the following:
- Section 1. Introduction: Provides the purpose, scope, audience and time horizon of the EU MON.
- Section 2. European MON Foundation: Describes the background, including an overview of the CNS Advisory Group recommendations on the need for a CNS PM and the definition of the MON, an outline of relevant NM Operational Excellence Programme work streams, and an inventory of related work.
- Section 3. European MON: Details the proposed design principles for the European MON.
- Section 4. Considerations in defining national MON: Explains important considerations for defining a MON at the national level.
- Appendix 1. Current State of the European CNS Infrastructure (the baseline): Establishes the baseline of current CNS infrastructure, performance levels, and challenges.
- Appendix 2. National MON Design Guidance: Provides guidelines for national MON design.
- Appendix 3. Application Regulatory Requirements and Reference Material: Summarises relevant legislation and reference material.
- Appendix 4. CBA Template for Local Infrastructure: Includes a CBA template for assessing local infrastructure.