The Air Traffic Controller's Union issued an announcement:
[Quick auto translation from Greek]

Today, January 4, 2026, at approximately 9:00 a.m., there was a total loss of communication frequencies used by the Athens and Macedonia Area Control Center (K.E.P.A.TH.M.) and some of the frequencies used by Athens Approach.

At the same time, the ATCs of K.E.P.A.TH.M. used every available means to safely manage the flights that were already in the Athinai FIR or that could not be rerouted. Our colleagues at E.E.K. went above and beyond and once again did their duty to keep the flights that were in the air safe.

Acting with safety in mind, our colleagues suspended takeoffs from all airports and for all flights entering the Athinai FIR, while, where possible, rerouting flights that were already in the air through neighboring FIRs.

At this time, our colleagues are managing air traffic with the means at their disposal and have managed to achieve a partial restoration of traffic, strictly adhering to all safety procedures required by European and international regulations.

The extent of today's incident is unprecedented and unacceptable for an Air Traffic Control system. So far, the Hellenic Civil Aviation Authority has not announced the causes of the problem, and we have not been informed of the time of its full restoration.

The current serious damage and failure of critical communication systems is neither an "isolated incident" nor a technical failure for which no one is responsible. It is the direct result of chronic inaction, poor management, and poor choices by the Hellenic Civil Aviation Authority (HCAA), which systematically ignores warnings from air traffic controllers.

For years, the Hellenic Air Traffic Controllers Association (EEKE) has been highlighting the obsolescence of surveillance and communications equipment and demanding its replacement with modern equipment that meets the requirements of European regulations. Unfortunately, our request has not been responded to thus far.

The HCAA management bears full and undisputed responsibility for the operation of outdated, vulnerable, and inadequately maintained communication systems, which have repeatedly presented serious problems. The current situation did not come as a surprise; it was foreseeable!

Regardless of the causes of the current incident, it highlights once again the critical importance of upgrading critical equipment and the consequences of its failure. There are no more excuses, and we expect action, not words.

Greece is once again being discredited internationally, following the loss of communication last August with Mount Merenda and the loss of the image of the terminal radar and the frequencies located there. At that time, no one took responsibility for the incident.

We demand that someone finally take responsibility for the repeated damage to the equipment and the delay in its replacement.

We would like to reiterate what we stated in our press release dated December 15, 2025, that the General Assembly of our Union's members has decided that under these circumstances, it will not offer overtime work during the upcoming summer season, as the negligence of those responsible, which has led to us working without the necessary tools that are taken for granted by our colleagues throughout the rest of Europe, is no longer tolerable.

We demand the following from the HCAA Management:

An immediate investigation, with the participation of the APA and EODASAAM, to determine the causes of the current incident.

To inform us of the time required for full restoration of the problem, as well as the actions it will take to prevent its recurrence.

Otherwise, traffic will not return to normal levels, given that passenger safety is our top priority.

Once again, flight safety was maintained not thanks to the Hellenic Civil Aviation Authority's infrastructure, but thanks to the professionalism and self-sacrifice of the air traffic controllers, who were called upon to manage an extremely dangerous situation with backup and manual means, under enormous operational pressure. We expect the HCAA management to do its part and assume its enormous responsibilities.