UPDATED: Greece says a radio failure that grounded flights is unlikely to be a cyberattack

Greece’s transport minister said Monday that a major radio communications failure that shut the country’s airspace a day earlier is unlikely to have been a cyberattack, though the cause remains under investigation.

Flights across Greece were grounded, diverted or delayed for several hours Sunday after noise was reported on multiple air traffic communication channels.

“It does not appear to be a cyberattack,” Transport and Infrastructure Minister Christos Dimas told public broadcaster ERT.

He described the disruption as “a very serious incident” but stressed that passenger safety was never at risk.

The Greek Civil Aviation Authority said noise across all channels, including backup systems, triggered the shutdown, which lasted several hours before operations were gradually restored.

Incoming flights were diverted to several countries in the region, creating a large backlog and leaving thousands of passengers stranded.

The Air Traffic Controllers’ Association said the outage underscored its calls to modernize and replace outdated equipment.

A judicial inquiry and an internal investigation were launched Monday into the cause of the outage.

Officials described the incident as unprecedented in scale, delaying dozens of flights during one of the busiest weekends of the holiday season.

Greece’s civil aviation authority said an indeterminate “noise” impacted radio channels, but the cause was not clear.

“The ‘noise’ observed in the frequencies was in the form of continuous, involuntary emission,” it said in a statement.

The disruption affected flights across the country for several hours, with authorities only able to service flyovers.

“For some reason all frequencies were suddenly lost .. We could not communicate with aircraft in the sky,” Panagiotis Psarros, chair of the Association of Greek Air Traffic Controllers, told state broadcaster ERT.

He later told Reuters that the outage highlighted the vulnerability of an aging system, which he said should have been replaced many years ago.

“We work with the most antiquated systems…in Europe,” he said.

By Sunday afternoon, limited services were restored after pilots switched to backup frequencies to keep in touch with controllers on the ground. Around 45 flights were leaving Greek airports every hour by late afternoon, an official said.

Christos Dimas, Greece’s infrastructure and transport minister, said the incident did not compromise flight safety.

‘UNPRECEDENTED’ OUTAGE

The air traffic controllers association said the breakdown affected all frequencies used on the ground, and some frequencies used by Athens Approach, an air traffic control unit responsible for managing aircraft flying in and out of Athens’ Eleftherios Venizelos airport.

Among its responsibilities are radar monitoring for safe separation of aircraft in the sky as well as issuing instructions on speed, and altitude levels.

The association said controllers were using all means at their disposal to ensure the safety of flights, calling the scale of Sunday’s incident “unprecedented and unacceptable”.

Psarros said the problem seemed to be a collapse of central radio frequency systems at the Athens and Macedonia area control systems, the largest air control facility in the country. It monitors the Athens Flight Information Region, a vast expanse of airspace under the control of Greek authorities.