Federal officials expect transportation systems will largely return to normal operations by Saturday, following a massive IT outage for Windows users that knocked out systems for transportation, delivery and health care. Airports on Friday were crowded with stranded travelers as major U.S. airlines grounded flights. Several health-care providers delayed some scheduled procedures. Emergency 911 call service was disrupted in some areas. Cybersecurity company CrowdStrike pointed to a defect in an update it had delivered for Microsoft’s Windows systems. Microsoft and CrowdStrike said the underlying problems were being fixed, but the incident underscored how a software glitch can have profound ripple effects. Businesses around the world reported issues with Microsoft Windows overnight Thursday into Friday, with users citing “blue screen of death” (BSOD) errors. At least some systems resumed functioning shortly afterward, but companies across multiple industries were affected...