The strike topped the 300 flights a day Ryanair had to cancel last month when cabin crews in Belgium, Portugal and Spain went on strike for 48 hours.
A Dutch court also rejected a case from Ryanair seeking to block pilots in the Netherlands from joining Friday’s strike, but the Irish airline said all of its flights there would run as scheduled.
Shares in the airline were 1.4 percent lower at 13.36 euros by 0825 GMT, having fallen 18 percent since the action ramped up in mid-July to stand well below the 14.21 euros they slumped to in December when Ryanair shocked markets by recognizing unions.
Ryanair operates more than 2,000 flights a day, serving 223 airports across 37 countries in Europe and North Africa, and insists it will not change the low-cost model that transformed the industry and has made it Europe’s most profitable airline.
At Charleroi Airport, Belgium’s second largest and a major Ryanair hub in the region, striking staff gathered in the departure hall and held up banners reading “Ryanair must change- Respect us”.
“Ryanair is the only multinational in Belgium that doesn’t respect the Belgian law and that’s not normal,” said Didier Lebbe, a representative of union ACV-CSC, whose demands include securing its pilots pay when they are on stand-by.
Apologizing to customers, Ryanair said in a statement that it took every step to minimize the disruption and called on striking unions to continue negotiations instead of calling any more “unjustified strikes.”
It has further angered unions by threatening to move jobs away from bases affected by the stoppages, and began carrying that out in Dublin where it cut its winter fleet by 20 percent and put over 300 employees on preliminary notice.
Ryanair has said that strike action will hit average fares because it takes up seats that it could otherwise have sold at a high last-minute price.