The outdated communications systems that continue to underpin air traffic management in Greece are at the heart of the decision to suspend the Athens FIR on Sunday, 4 January 2026.

According to the Commission of Inquiry, the widespread communications blackout was not caused by a cyber attack or external interference, but by the malfunction of old technology systems that are no longer supported by their manufacturers and lack modern tools for monitoring and fault diagnosis.

The finding thus serves as a clear warning. It highlights that the delay in the transition to modern digital communication infrastructure increases the risk of similar incidents recurring. It therefore recommends speeding up the replacement of old systems with new, modern networks, strengthening coordination between the Civil Aviation Authority and the telecommunications provider, and improving the supervision of critical frequencies.

“Digital noise” and uncontrolled transmitters

On the morning of January 4, just before 9 am, air traffic controllers began noticing intense and constant noise on aircraft communication frequencies. Communications, both with aircraft and between control centres and airports, became extremely difficult or even impossible. Even backup and emergency frequencies were affected, creating an unprecedented picture of generalised system failure.

As the finding explains, the cause of the problem was the occurrence of a kind of “digital noise“. Simply put, different devices and communication lines that should be operating in perfect synchronization lost their common rhythm.

When this happens in old systems, some transmitters may turn themselves on and start transmitting continuously without human command. This is exactly what happened, resulting in the frequencies being “filled” with noise and normal conversations being blocked.

The situation was exacerbated because these systems do not provide technicians with the ability to see in real time exactly what is happening.

There are no detailed logs, nor a complete picture of end-to-end network operation. So while from the telecommunications provider’s perspective the circuits typically appeared “active”, in practice the communication had broken down. Diagnosis of the problem was delayed and restoration came only after a total restart and resynchronization of the network.

Zero rate to prevent the worst from happening

For reasons of flight safety, the competent authorities proceeded to suspend take-offs and impose a zero rate in Greek airspace. At that time, dozens of aircraft were already in the air and were served by special emergency procedures.

Despite the seriousness of the incident, no incidents were recorded that posed an immediate risk to flight safety, a fact attributed to the timely reaction of controllers and crews.

The Commission explicitly excludes the possibility of a cyber-attack or deliberate interference. Checks have shown that there was no unauthorised access to the systems, nor any transmission from an external source. On the contrary, all the evidence points to the conclusion that this was a technical infrastructure failure, which most clearly demonstrated the limits and weaknesses of the existing systems.

Appointment of a technical consultant

In the wake of the findings of the serious incident of 4 January 2026, which highlighted critical weaknesses in air navigation systems and serious logistical issues, the appointment of a technical advisor by EUROCONTROL to support the Ministry of Infrastructure and Transport’s Action Plan.

The relevant agreement was reached during the meeting in Brussels between the Minister of Infrastructure and Transport, Christos Dimas, and the Director General of EUROCONTROL Raúl Medina Caballero, to accelerate the implementation of the interventions that are now deemed necessary following the conclusions of the report.

According to the Ministry, the technical advisor will contribute both to the institutional reform of the sector and to the modernization of air navigation systems, two axes that the finding identified as critical to the restoration of operational safety and reliability of air traffic control.

Air traffic controllers are up in arms about the finding

Air Traffic Controllers describe the conclusion of the investigating committee’s findings on the serious incident of January 4, 2026, as a complete vindication of their long-standing complaints.

As the Air Traffic Controllers Association of Greece points out, the conclusion confirms that Air Traffic Control in the country operates with outdated equipment, without any substantial safety guarantees.

According to the controllers, the history of the events clearly depicts the intense pressure conditions under which the shifts were working on the morning of the incident, as well as the administrative confusion that prevailed. As they point out, the report itself documents long delays in diagnosing the cause and a lack of effective cooperation among the Civil Aviation Authority’s management.

The auditors give particular weight to the report’s statement that it was not possible to determine the exact cause of the incident, which they attribute to “many reasons. As they note, this finding, coupled with the assumption that no meaningful operating guarantees can be provided for the voice communications system, raises serious questions about the safety of day-to-day operations.

The auditors emphasize that the safe outcome of the incident was not the result of administrative manipulation, but was due solely to their professionalism and the decision to imposezero rate, i.e., the closure of airspace. As they say, the finding clearly demonstrates that this decision prevented a potentially much more serious development.

At the same time, they express grave concern that, despite the conclusions of the findings, the Administration chose to immediately restore capacity to 100%, without a prior safety assessment and without a gradual increase. As they point out, this contradicts what is required by European regulations and makes it impossible to safely handle the increased summer traffic.

Finally, the Auditors reiterate the issue of the delays in the installation of the new VHF transponders, arguing that if it were not for these administrative failures, the equipment would have already been received and the incident might have been avoided. In view of the above, they are calling for immediate policy intervention by the Ministry of Infrastructure and Transport to reduce capacity and ensure flight safety.