NEW : Estimated 4,000 pilots at German airline Lufthansa begin four-day strike . The pilots union says strike focuses on pay and conditions issues . Many of Lufthansa 's pilots have been working without a contract since March and more than 90 percent of the union 's members voted to strike , said Jorg Handwerg , a pilot and representative for the union . Germany has been hit by a series of strikes in recent years over wage increases, pensions and other labor matters. Lufthansa flies to 80 countries with its main hub being Frankfurt , Germany .
NEW : Estimated 4,000 pilots at German airline Lufthansa begin four-day strike . The pilots union says strike focuses on pay and conditions issues . Germany has been hit by a series of strikes in recent years over wage increases, pensions and other labor matters. Lufthansa flies to 80 countries with its main hub being Frankfurt , Germany .