Summer flights could face disruption as staff at one of Europe’s air traffic control (ATC) centres are threatening to strike.

       One of Eurocontrol’s trade unions, Union Syndicale Bruxelles (USB), has “announced a period of six months during which industrial action could take place”.

       The union has given this "pre-warning" of industrial action due to persistent staff shortages of up to 25 per cent and other policies it considers detrimental.

       No specific dates have been confirmed but strikes could begin with just five days notice during the busy summer season.

       "We are currently negotiating with the Director General and his team and are hopeful of a positive outcome, but we have not received written assurances or agreements yet," USB says.

       Eurocontrol and other industry experts have said they expect minimal disruption but issues with ATC are now shaping up to be the biggest source of concern for travellers this summer.

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       Where could strikes take place?

       Eurocontrol coordinates ATC across Europe. It helps aircraft to easily travel from one country’s airspace to another.

       The staff threatening to strike are based at the organisation’s Network Manager Operations Centre (NMOC) which handles over 10 million flights every year.

       Travelers wait in line outside the terminal building to check in and board flights at Amsterdam's Schiphol Airport.AP Photo/Peter Dejong, File

       It plays a pivotal role in managing, streamlining and improving air traffic operations across the continent, checking 96,000 messages from airlines and pilots every day.

       Before the pandemic, the NMOC was managing more than 37,000 flights a day. This summer that number is set to return to around 33,000 as demand for flights starts to approach what it was before COVID-19.

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       Would an ATC strike cause delays and cancellations?

       Eurocontrol says that as no notice of specific industrial action has been received, it is “premature to speculate on any potential impact”.

       Leading industry body Airlines for Europe (A4E) also says that as dates have not yet been announced the “possible impact remains to be determined”.

       “A4E understands that Eurocontrol’s air traffic control (ATC) services will not be affected,” a spokesperson said.

       “Therefore its impact on passengers could be limited, unlike the wave of national strikes that impacted air travel in Europe since the beginning of the year, ruining travel for millions of passengers,”.

       There are still concerns, however, after Eurocontrol warned that this summer will be “challenging” for the aviation industry in Europe. It said that pressure on airspace from the war in Ukraine combined with an increased number of flights could lead to overcrowded skies.

       Other ATC strikes are already adding further pressure. Last month, Ryanair cancelled more than 900 flights across Europe - 1 per cent of its total number. The airline blamed the 60 days of industrial action so far this year from controllers in France for causing the disruption.