At Greece's main airport, Eleftherios Venizelos in Athens, passengers were stuck in long queues as several domestic and international flights were delayed or grounded altogether, an AFP reporter saw.
The radio frequency loss was first reported around 0700 GMT.
"No plane landed or took off for at least two hours," said the press office at Athens airport, where 31.6 million passengers transited in the first 11 months of 2025.
For up to three hours, most aircraft headed for Greek airports were redirected to Turkey, according to Greek public television ERT.
Air traffic had been resuming progressively since 1100 GMT, authorities said.
Panagiotis Psarros, head of Greece's air traffic controller union, called the incident "very serious" and blamed what he said was "obsolete" airport equipment.
© 2026 AFP