By Helena Soderpalm STOCKHOLM (Reuters) -Scandinavian airline SAS and unions representing striking pilots were unable reach a collective bargaining agreement on Wednesday, with negotiations to resume on Thursday as a crippling strike will enter its 11th day. The 75-year old carrier was struggling even before the pandemic hit in 2020 due to high costs and growing competition from low-cost carriers. The pilots strike, which started in July 4, cost $10 million to $13 million a day and forced SAS to cancel more 1,200 flights at the peak of the summer travel season. “We have decided to stop tonight…