So far, the evidence being examined by the competent services of the Ministry of Infrastructure and Transport converges on a technical malfunction rather than an external threat as the cause of the serious incident that grounded flights on January 4 and led to extensive restrictions—and at times a complete suspension—of air traffic within the Greek FIR.

Although initial reports spoke of “interference” on airspace frequencies, even leaving open the possibility of external intervention, scenarios involving a cyberattack or an asymmetric threat now appear to be receding. Checks carried out through specialized frequency-monitoring flights, as well as analysis of logs and spectrum data, revealed no indications of external interference.

According to the information gathered, air traffic controllers did indeed hear interference on the frequencies. However, the critical issue was not the reception of messages from aircraft, but the inability of controllers themselves to transmit messages—an element that strengthens the assessment that the malfunction originated within the system.

The Most Likely Scenarios

1. A problem in the telecommunications infrastructure

The Civil Aviation Authority uses leased telecommunications circuits to transfer audio and data between antennas, radars, and control centers. Information suggests that technical work had previously been carried out on a specific data transmission link, which may have caused a failure or incompatibility in system operation. Such a problem could generate internal interference and loss of communications without any external involvement. What is particularly concerning, according to informed sources, is that these are critical infrastructures with insufficient backup redundancy.

Moreover, the malfunctions identified yesterday were not limited to air traffic control radio frequencies. According to reports, the problems extended to the telecommunications network of the HCAA’s central services, with the infrastructure allegedly operating throughout the day without telephone communications or internet access.

2. Old equipment with inadequate backup systems

HCAA equipment is described as largely outdated, with systems that have not been modernized for decades. Sources from the Ministry of Infrastructure and Transport stress that piecemeal upgrades are not possible for systems of such critical importance, as major procurements and full modernization require time—estimated at no less than two years.

According to the HCAA, security protocols were activated immediately after the problem emerged, leading to a sharp reduction in flights and, where deemed necessary, their temporary suspension. These measures eliminated any risk to flight safety but clearly exposed the system’s weaknesses.

Why the Hellenic Air Force Was Not Affected

In Greece, two entirely separate and autonomous air traffic management systems operate. The first, under the authority of the Civil Aviation Authority, is the one familiar to the public and serves civilian flights in the Athens FIR. It includes radars, telecommunications infrastructure, and air traffic controllers managing civil aviation.

The second system belongs to the Hellenic Air Force and falls under the Ministry of National Defense. It has fully independent infrastructure, its own nationwide radar network, autonomous transmitters and receivers, specialized air defense controllers, and a separate Air Operations Control Center headquartered in Larissa.

The two systems operate in parallel but without any functional or technical interconnection. They are fully autonomous networks with different infrastructures, personnel, and procedures. This means that technical problems or malfunctions in the civil air traffic control system do not affect the military system of the Hellenic Air Force.

Investigation Continues

Yesterday’s incident in the FIR was particularly serious, but government sources note that it is not an isolated phenomenon at a European level. A similar paralysis occurred in London a few months ago, lasting two days—a point cited to show that such failures are not exclusively a “Greek phenomenon,” but also affect countries with enormous daily air traffic volumes.

This, of course, does not downplay what happened at Greek airports. The investigation continues, with authorities emphasizing that the goal is not only to fully clarify the causes but also to adopt measures to prevent similar incidents. Otherwise, the impact on air transport and the country’s international image could be significant.

Measures and Action Plan

Within this framework, authorities report that a package of measures has already been implemented to reinforce the systems and address the most obvious weaknesses. At the same time, additional interventions are being examined to strengthen redundancy and reliability in critical telecommunications infrastructure.

The Ministry of Infrastructure and Transport reminds that an Action Plan is underway for upgrading and modernizing air navigation systems, in cooperation with European bodies (DG MOVE, EASA, and EUROCONTROL). The plan, with a completion horizon of 2028, includes 364 actions across seven main pillars, such as the development of Data Link services, upgrading the air traffic control system, implementing Performance-Based Navigation (PBN), developing Mode S radar, and applying Regulation CP1.

Sharp Criticism from Air Traffic Controllers

The Hellenic Air Traffic Controllers Association (EEEKE) issued a strongly worded statement, describing the “communications blackout” as a serious and unprecedented incident for the country’s air traffic control system. According to the statement, this was neither an isolated event nor a simple technical failure, but a crisis with clear systemic characteristics.

Controllers attribute the incident to the chronic aging and inadequate maintenance of communications and surveillance equipment, speaking of long-standing inertia and misguided management choices at the Civil Aviation Authority. They note that they have repeatedly warned about the risks posed by operating outdated systems without receiving a substantive response, stressing that yesterday’s collapse had been foretold.

Despite the severity of the situation, the EEEKE emphasizes that controllers at the Athens and Macedonia Control Centers made every possible effort to ensure flight safety. Colleagues went above and beyond, using every available means to safely manage flights already airborne or unable to be rerouted.

Finally, the controllers call for an immediate and thorough investigation with the participation of all competent authorities, as well as meaningful interventions to upgrade critical equipment. At the same time, they warn that under current conditions they do not intend to offer overtime work during the upcoming summer season, stressing that it is no longer acceptable for the system to operate without modern and reliable infrastructure.