 United, Delta, and Allegiant all requested ground stops with the Federal Aviation Administration citing communication issues. It seems their problem stems from an outage impacting cybersecurity firm CrowdStrike. American Airlines just released this statement saying, quote, we're aware of a technical issue with CrowdStrike that is impacting multiple carriers. American is working with CrowdStrike to resolve the issue as quickly as possible and apologize to our customers for the inconvenience.