A nationwide strike by the country’s largest private sector union group, GSEE, tomorrow is expected to disrupt air travel with Olympic Airlines canceling 51 flights, including 13 to overseas destinations. Olympic Airlines will operate one flight to each domestic destination and only one flight to each foreign country it serves, the airline said yesterday. The national air carrier will cancel four flights to Germany, three each to Britain and Italy, and one to France. The General Confederation of Greek Labor (GSEE) will join striking public sector workers, ADEDY, in protest against a shift in public sector work hours and labor market reforms. The government has scheduled to kick off in Parliament on Thursday talks on changes to the social security system. As a condition to participating in the scheduled discussions GSEE has called for research studies on the pension system and for the state to outline an agenda for talks.