Flights into Greece were temporarily grounded, delayed or diverted this month after an unexplained noise was heard over radio frequencies that are used to communicate with aircraft. The air-traffic radio blackout caused a loss of all frequencies, according to reports from the Association of Greek Air Traffic Controllers. The Hellenic Civil Aviation Authority told the media that the cause was a [quote] "continuous involuntary emission" [endquote] disrupting communications on the 4th of January.

Authorities said they were able to rule out any likelihood of a deliberate attack but they were continuing their investigation into what they called an unprecedented outage. It was suspected that the two-hour standstill was the result of some unknown technical issue. A report by the BBC said that one theory reported was that a station in the mountains near Athens had failed.

Greece's Ministry of Infrastructure and Transport said that there are plans to upgrade the country's aging air navigation systems and have the modernization in place by 2028.