Ryanair was among airlines that announced widespread disruptions, saying in a statement it canceled more than 400 flights affecting 70,000 passengers. The company said the strike affects all its flights over French airspace, as well as traffic in and out of French airports, and urged the European Union to reform air traffic rules.

In February, the Maryland Board of Public Works approved a $22 million contract for the project to help improve the airport’s safety and efficiency, in spite of budgetary pressures that limited spending to the state’s top priorities.