. risk factors 2013 201cif we are unable to obtain and maintain adequate facilities and infrastructure throughout our system and , at some airports , adequate slots , we may be unable to operate our existing flight schedule and to expand or change our route network in the future , which may have a material adverse impact on our operations , 201d 201cour business is subject to extensive government regulation , which may result in increases in our costs , disruptions to our operations , limits on our