# A Multi-Layer Secure Sharing Framework for Aviation Big Data Based on Blockchain
## 3 Analysis of ATM Big Data Sharing
### ATM System Concepts
#### 3.1.4 Constraints  
The International Civil Aviation Organization (ICAO) has explicitly identified the coordinated development of \"physical safety--operational efficiency--environmental sustainability--information security\" throughout the entire lifecycle as the overarching objective in the Global Air Traffic Management Operational Concept [22]. Under this macro-level guidance, these objectives can be further decomposed into specific constraints. Safety prioritizes the security of aircraft and personnel above all else, with ATM implementing multidimensional constraints through systematic risk management. ICAO's Standards and Recommended Practices (SARPs) and Procedures for Air Navigation Services (PANS) provide theoretical guidance for safe operations. At the operational level, ATM adopts a layered defense strategy for conflict management, strictly enforcing horizontal, vertical, and temporal separation standards to maintain aircraft operational risks within acceptable limits while incorporating the Traffic Collision Avoidance System (TCAS) as a safeguard. Additionally, quantitative management of air traffic controller workload ensures it remains within safe thresholds. Efficiency requirements primarily focus on optimizing airspace and airport resource allocation to reduce flight delays and lower operational costs. In practice, this involves multiple technical indicators and operational constraints such as airspace capacity limits, maximum acceptable delay thresholds, route optimization restrictions, and flow management constraints. To enhance efficiency, dynamic airspace management is achieved by balancing user preferences with airspace capacity limitations based on 4D trajectory requirements while mandating information sharing among all stakeholders including airlines, air traffic control, and airports to facilitate collaborative decision-making and improve airspace throughput. Environmental sustainability aims to significantly reduce the environmental impact of aviation activities through optimized operational procedures, ultimately achieving ICAO's global goal of net-zero carbon emissions by 2050. This is manifested in three key areas: (i) carbon emission control: implementing trajectory optimization techniques, strictly enforcing phased carbon emission limits under ICAO's CORSIA mechanism [24], and adopting sustainable aviation fuels; (ii) noise management: maintaining strict compliance with ICAO's day-night noise limits [25] and optimizing flight procedures to reduce noise during approach and departure phases; and (iii) energy efficiency: integrating real-time meteorological data to minimize unnecessary detours and implementing flexible airspace management strategies. Cybersecurity serves as a critical element in safeguarding global aviation safety, playing a vital role in ATM systems. ATM systems heavily depend on the availability of information and communication technologies (ICT), as well as the accuracy and confidentiality of data, all of which directly impact flight safety and efficiency [26]. As early as 1996, ICAO's ATNP Security Working Group identified that all ATM information transmitted via data links is vulnerable to tampering, replay, and forgery attacks, while the Communication, Navigation, and Surveillance (CNS) systems supporting ATM exhibit inherent vulnerabilities to Distributed Denial of Service (DDoS) attacks. With the continuous evolution of cyber threats, attacks targeting ATM systems are demonstrating broader impact and greater destructive potential. To address these growing cybersecurity challenges, ICAO has established a systematic standard framework. The 2019 Aviation Cybersecurity Strategy [27] for the first time elevated cybersecurity to a strategic priority, requiring member states to incorporate cybersecurity into their national aviation safety and security oversight systems.