The investigation committee’s report on the conditions that led to the blackout of Greek airport communications on January 4, resulting in the Athens FIR blackout, has been made public.
The report follows:
“The Investigation Committee’s report on the Athens FIR operational suspension incident on Sunday, January 4, 2026, was submitted today to Infrastructure and Transport Minister Christos Dimas. The committee was established by ministerial decision to clarify the exact causes of the problem that occurred in Athens FIR frequencies.
The committee, chaired by Civil Aviation Authority Director Christos Tsituras, included: National Cybersecurity Authority Director Michalis Bletsos, Colonel Dimitrios Zabakolos, Communications Engineer at General Staff of National Defense, EETT spectrum supervision deputy director Nikos Igoumenidis, a EUROCONTROL (European Organisation for the Safety of Air Navigation) representative, while an EASA (European Union Aviation Safety Agency) representative participated as observer.
The committee identified the Civil Aviation Service (YPA) and Hellenic Telecommunications Organisation (OTE) as involved entities, from whom it requested and received official reports of their actions, while also evaluating information obtained from interviews with officials from both organizations.
According to the experts’ report: the incident was caused by “digital noise,” which occurred due to desynchronization in a constellation of heterogeneous devices/interfaces terminating at KEPATHM installations, resulting in inadvertent activation/continuous transmission of a critical number of transmitters and degradation/interruption of critical telecommunications connections. Full restoration was achieved following resynchronization/restarts that followed traffic rerouting in the backbone network.
It is noted, among other things, that for flight safety reasons, full capacity restriction (zero rate) was imposed and emergency procedures were applied. Service restoration was gradual, while full restoration was completed at 16:53 local time, following voluntary action by the telecommunications provider.
Based on reports on the ECCAIRS platform and APA evaluation, the incident was classified as low risk (Green Area), with no reported minimum separation violations. Additionally, no evidence emerged of cyberattack or external malicious interference.
Regarding aviation security issues, it is stated that no aviation security issue was identified in terms of exposing aircraft to direct or indirect danger.
In its findings, the committee notes that YPA’s existing Voice Communication System (VCS) and critical telecommunications infrastructure used to support it are based on outdated technology (SDH – Synchronous Digital Hierarchy) that is unsupported by the manufacturer, without the possibility of providing substantial operational guarantees.
In its report, the Special Committee concludes with the following recommendations:
a) expediting transition to VoIP (Voice over IP) technology, by completing procurement procedures – installation and operational deployment of the new VCS/RCS (Voice Communication System / Radio Communication System) and 495 new transceivers,
b) establishing a permanent joint YPA-OTE immediate response mechanism and standardized crisis procedures with testing/training under APA supervision,
c) enhancement with telemetry/remote control and capability to perform end-to-end diagnostic checks at key points,
d) strengthening radio spectrum supervision by EETT for early detection of interference/anomalies, and
e) relocation of KEPATHM facilities to a more suitable environment, aimed at reducing systemic operational risks and dependencies to ensure uninterrupted and safe provision of aviation services.
