US airlines were hit by system-wide computer outages on Monday related to problems with the Aerodata planning weight and balance program, the Federal Aviation Administration said. After reporting problems along with several major peers, however, Southwest Airlines Co. said on Twitter that it had received word that the problem had already been resolved and that systems would be back up soon. Earlier, carriers had reported problems through their social media accounts, with United Airlines saying it was unable to create paperwork as a result. The No. 1 US carrier American Airlines said the outage was affecting regional carriers nationwide. Canada’s Alaska Air Group Inc. also said on its social media account that it was experiencing a system-wide outage.