Flights across Greece were halted for hours on Sunday after a collapse of radio frequencies crippled air traffic communication, stranding thousands of travellers during one of the busiest holiday weekends.

Air travel across Greece was thrown into disruption on Sunday after a widespread failure of radio frequencies left air traffic controllers unable to communicate with aircraft, forcing airport operations into near standstill conditions.

The outage began early in the day and rapidly escalated, affecting dozens of flights nationwide. While some overflights across Greek and regional airspace continued, restrictions were imposed on airport departures and arrivals, according to the Hellenic Civil Aviation Authority.

By Sunday afternoon, limited services were gradually restored after pilots and controllers switched to backup frequencies to maintain basic communication. Authorities said flight movements were cautiously increased, with up to 45 departures per hour leaving Greek airports by late afternoon.

Air traffic controllers said the cause of the blackout remained unclear. Panagiotis Psarros, head of the Association of Greek Air Traffic Controllers, told state broadcaster ERT that all main communication frequencies were suddenly lost, leaving controllers unable to contact aircraft in the sky.

The breakdown affected all ground frequencies and some used by the Athens Approach unit, which manages aircraft arriving at and departing from Eleftherios Venizelos Airport. The unit is responsible for radar monitoring, aircraft separation, and issuing instructions on speed and altitude.

The controllers’ association described the scale of the incident as unprecedented and unacceptable for a modern air traffic control system, stressing that safety was maintained only through emergency measures.

Psarros said the failure appeared linked to a collapse of central radio frequency systems at the Athens and Macedonia area control centres, which oversee the Athens Flight Information Region, a vast stretch of airspace under Greek control. He added that ageing equipment had been repeatedly flagged as a concern in the past.

Greek authorities said investigations were continuing to determine the cause of the blackout, which disrupted travel plans for thousands at the peak of the holiday season.

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