KLM cancels flights as crowds jam Amsterdam's Schiphol
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"These cancellations in KLM's flight schedule also contribute to reducing the workload" for its own staff, the airline said.
Schiphol -- Europe's busiest airport in terms of aircraft movements in 2019 when more than 70 million passengers passed through its gates -- saw numbers plunge during the coronavirus pandemic.
But after the Dutch government dropped its last major Covid-19 restrictions in mid-March, passenger numbers once again took off, peaking around the Easter weekend which was still continuing.
The International Air Transport Association (IATA) condemned Schiphol's request to airlines as "outrageous".
The strike came on the first day of the May school holidays, with many families going on holiday for the first time since coronavirus restrictions were dropped.
"The crowds are caused by the May holidays and the personnel shortages in the aviation sector," it said.
The airport said it would have talks with airlines on Sunday to discuss the problem.
Meanwhile, at least one travel company has moved operations to the nearby and less busy Rotterdam The Hague Airport.