Flight operations across Greece are gradually resuming following a technical problem with the Athens Flight Information Region (FIR) that disrupted arrivals and departures at Athens International Airport and regional airports on Sunday morning, Athens International Airport has announced.

Prioritizing safety, up to 35 departures and arrivals are being handled at Greek airports, the Hellenic Civil Aviation Authority (HCAA) said early Sunday afternoon, adding that it continues to investigate the incident in coordination with external agencies.

The authority described the scale of the technical issue as unprecedented and said further announcements will follow.

The problem appears to be linked to the central radio frequency systems of the Athens and Macedonia Area Control Centers, which are responsible for coordinating all flights entering Greek airspace. The radio frequencies serving the affected center went out of operation early Sunday, grounding planes and affecting schedules, while aircraft already in the air continued to operate normally.

A directive issued by authorities allowed only overflights – aircraft passing through Greek airspace without landing – while service was being restored.

Passengers at Athens airport have reported long waits amid overcrowded departure areas and uncertainty about flight departures.