Paris Charles de Gaulle airport employees protest with trade union flags outside a terminal as they stage a strike to demand higher wages at Roissy Charles De Gaulle Airport, north of Paris, on June 9, 2022. (GEOFFROY VAN DER HASSELT / AFP)

Labor strife and staffing shortages have European airports clamoring to find more workers, minimize cancelled flights and reduce headaches for travelers during the busy summer season.

Workers at France's Charles De Gaulle airport went on strike on Thursday for more pay, with a quarter of flights cancelled. In Italy, crews from budget carriers Ryanair, easyJet and Volotea walked off the job on Wednesday.

Workers at France's Charles De Gaulle airport went on strike on Thursday for more pay, with a quarter of flights cancelled. In Italy, crews from budget carriers Ryanair, easyJet and Volotea walked off the job on Wednesday

Ryanair cabin crew could strike in Europe this summer, after talks ended with two Spanish unions, according to a statement by unions SITCPLA and USO.

Airport managers are struggling to quickly recruit and process new hires, as a rebound in air travel from a pandemic-induced slump leads to cancelled flights and hours-long lines.

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Airlines, battered by slumping travel during the pandemic, have been counting on a strong summer, as fares rise to offset higher fuel costs. Some countries are also banking on tourism to revive hard-hit economies.

The head of airline trade group International Air Transport Association has said heavy congestion also occurred before the pandemic and is now limited to certain airports, aggravated by delays to get security badges required for newly-hired staff.

In North America, Canada's busiest airport is allowing some staff who have not yet obtained their badges to work temporarily under supervision by vetted employees, said Tori Gass, a spokeswoman for the Greater Toronto Airports Authority.

The temporary pass was recently introduced at Toronto Pearson International Airport in response to the large volume of appointments for restricted area identity cards (RAIC), Gass said. It takes roughly 45 days to get the cards.

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Transport Canada said it received 13,722 applications nationally for clearances required for employees like airport ramp agents or baggage handlers in the first quarter of 2022, up from 5,968 requests during the same period in 2021.

Pearson is wrestling with planes stuck at gates and hours-long security lines due to staffing shortages.

An screen displays a notification of travel disruptions as Paris Charles de Gaulle airport employees stage a strike to demand higher wages at Roissy Charles De Gaulle Airport, north of Paris, on June 9, 2022. (GEOFFROY VAN DER HASSELT / AFP)

Canadian Transport Minister Omar Alghabra on Wednesday said he is working with partners to bring in more screening officers.

"We're acting," Alghabra told reporters.

In Europe, Dublin and Heathrow airports are recruiting screeners, while Schipol Airport in Amsterdam is raising wages for staff.

Spain on Tuesday announced the hiring of 500 additional police to staff passport controls at busy airports and tourist destinations including Madrid.

In the United States, airports are generally avoiding such heavy congestion. Still, a staffing crunch has forced airlines to cancel flights and trim summer schedules.

Alaska Air Group Inc last month was forced to cancel 4 percent of its flights because of staffing woes. Delta Air Lines, which cancelled about 700 flights over the four-day Memorial Day holiday, plans to cut flights through August.

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Spain's interior minister attributed reports of congestion at border controls to multiple flights arriving at the same time. But CEHAT, the country's largest business group for hotels and lodging, said the delays could have been prevented since they are related to the end of free travel of British citizens to Spain due to Brexit.

"This situation should not have caught us off guard," CEHAT president Jorge Marichal said in a statement on Wednesday.