A three-day strike by pilots at Germany's biggest airline, Lufthansa, has entered its final day.While hundreds of flights remained cancelled at airports across Germany on Friday, pilots' union Vereinigung Cockpit confirmed that the strike would end at 11.59 p.m. (2159GMT).The three-day action has led to the cancellation of 3,800 flights, affected 425,000 passengers and is expected to cost the airline €75 million (US$100 million).The airline said it had managed to operate about 10 percent of its flights using 190 volunteer pilots, including about 100 managers who held pilot licenses.Vereinigung Cockpit, which represents about 5,400 pilots, staged the walkout in order to preserve an in-house agreement on early retirement along with a demand for a 10 percent pay rise.The strike is believed to be the biggest in Lufthansa’s history and has led to losses of tens of millions of euros in its Lufthansa, Lufthansa Cargo and low-cost carrier Germanwings passenger operations.