French air traffic controllers launched a nationwide walkout on Thursday in protest against workforce shortages and outdated systems, compelling budget airline Ryanair to scrap 170 flights and disrupt the plans of more than 30,000 travelers.

The French civil aviation authority DGAC instructed carriers to modify their flight schedules, including at Roissy Charles de Gaulle airport in Paris, a major European transportation hub, forcing airlines to cancel departures, reported Reuters.

Air France, the nation's largest carrier, announced schedule adjustments while preserving all long-distance routes, and British Airways, which is owned by IAG, deployed bigger aircraft to minimize service interruptions. The low-cost airline Easyjet announced it would cancel 274 flights spanning Thursday and Friday.

The industrial action coincided with the start of Europe's peak summer vacation season, which is traditionally one of the year's most intensive travel periods.

"Once again, European families are held to ransom by French air traffic controllers going on strike," Ryanair CEO Michael O'Leary said. "It makes no sense and is abundantly unfair on EU passengers and families going on holidays."

He urged European Commission President Ursula von der Leyen to reform air traffic control services.

UNSA-ICNA, the second-largest union representing French air traffic controllers, cited chronic worker shortages, aging infrastructure, and toxic workplace practices as the reasons for the walkout. The separate labor group USAC-CGT criticized the DGAC for failing to recognize controllers' discontent.

"The DGAC is failing to modernize the tools that are essential to air traffic controllers, even though it continues to promise that all necessary resources are being made available," UNSA-ICNA said in a statement. "The systems are on their last legs, and the (air traffic control) agency is constantly asking more of its staff to compensate for its difficulties."

The controllers' grievances mirror concerns in the United States over outdated infrastructure and worker shortages.

Philippe Tabarot, France's transport minister, called the unions' demands "unacceptable".

The DGAC said airlines cut one in four flights out of Paris airports on Thursday, and nearly half of departures from the capital on Friday. In other locations around France, airlines were ordered to reduce the number of flights by between 30 percent and 50 percent.

"Despite these preventative measures, disturbances and significant delays are to be expected," the agency warned.

Luxair Luxembourg Airlines cautioned that "additional delays and schedule changes are possible across other destinations, as air traffic rerouting and capacity constraints may cause knock-on effects throughout the network".