'Unprecedented': Radio Frequencies' Collapse Cripples Air Traffic Across Europe; Thousands Stranded As Greece Airspace Disrupted

New Delhi: Flights across Greece were grounded for several hours on Sunday after a collapse of radio frequencies crippled air traffic communications, stranding thousands of travellers and bringing airport operations to a virtual standstill.

Authorities said the disruption began at 8:59 a.m. local time (0659 GMT), when most aviation radio frequencies were hit by massive interference, forcing a precautionary shutdown of Greek airspace.

Authorities called the disruption 'unprecedented,' with mass flight delays hitting travelers during one of the busiest holiday windows.

What's Behind the Chaos

Greek aviation officials reported a mysterious, 'continuous' signal interference that crippled radio channels nationwide. While flights passing through Greek airspace (flyovers) continued, domestic and arriving flights were stalled for hours by the unexplained transmission.

"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 said, as per news agency Reuters.

Underlining further, he added that the outage highlighted the vulnerability of an aging system, which he said should have been replaced many years ago.

Limited Services Restored

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

According to the air traffic controllers association, the outage was widespread, neutralizing all ground-based frequencies. The interference also hit segments of the Athens Approach, the critical unit tasked with guiding traffic in and out of the nation's capital."

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.