(CNN) -- Thousands of travelers face disruption and canceled flights Wednesday as French air traffic controllers go on strike for a second day over a European Union plan to update rules governing European airspace.
About half the scheduled flights at Paris' Charles de Gaulle Airport have been canceled because of the strike, the airport said.
There are usually about 600 flights a day from the airport at this time of year, it said. Short and medium-haul flights are those most affected for the 200 airlines that operate out of the airport.
About 2,000 flights across Europe were canceled Tuesday, the first day of the strike, the air traffic agency Eurocontrol said.
The strike has led to the cancellation of 27 flights Wednesday from London's Heathrow Airport -- 14 arriving and 13 departing, the airport said.
Most of the flights were going either to or from Charles De Gaulle, Toulouse and Marseille airports, it said.
EasyJet said 66 flights to or from the United Kingdom had been canceled Wednesday.
"These are largely contained to France and Spain although other destinations may be affected" by the resulting delays, it said in a statement.
Travelers are encouraged to check with EasyJet for updates, particularly if they are flying to or from France, Spain and Portugal.
"EasyJet is contacting customers affected by cancellations, and those passengers will be entitled to a refund or to book an alternative flight," the airline said.
A spokeswoman for Charles de Gaulle Airport said it hopes to return to normal service Thursday when the strike is due to end.
The European Transport Workers' Federation said air traffic workers in 11 European countries were taking action Wednesday to voice their opposition to plans involving a single European airspace.
Air traffic controllers are on strike only in France and Hungary, however, with other action including gatherings and walkouts, said Francois Ballestero, the union's political secretary.
The union's action follows the European Commission's adoption Tuesday of a new package on the "Single European Sky," it said.
It believes the package, known as SES2+, would jeopardize jobs and put cost savings and competitiveness ahead of safety considerations.
The European Commission says EU rules on air traffic management must be updated to boost performance and improve oversight, otherwise predicted increases in air traffic will cause major delays.
It said the new rules would mean lower costs for airlines and more direct routes, which would help keep ticket prices down for travelers, while helping airlines return to profit. Shorter routes and fewer delays would also mean lower greenhouse-gas emissions, it said.
The Single European Sky program was first launched in 2004 to improve coordination between the 27 member states' air traffic authorities and cut delays.