 That's the sort of message travelers are hearing at airports, big and small, as the FAA says airlines like Delta, United, American, and Allegiant all grounded flights, with only Americans saying they're slowly starting to come back online. The disruptions come as cybersecurity firm CrowdStrike acknowledges an update it rolled out to computers running Windows triggered massive worldwide IT outages. The company is stressing that this is in no way the result of a cyber attack.