Airlines resume service after a massive global IT outage disrupted computer systems

A massive IT outage caused massive disruptions across the world on Friday, impacting flights, banks and other major institutions.

By Friday afternoon, it appears computer systems have for the most part been restored, but some companies and agencies said residual effects could continue throughout the day.

During the outage, the Federal Aviation Administration said that several airlines requested assistance with ground stops for their fleets. Many major airlines said they will offer travel vouchers this weekend, allowing passengers to adjust their itineraries without paying change fees.

FlightAware reported that over 1,900 U.S. flights had been canceled as of late Friday morning. Additionally, more than 3,000 flights have been delayed. Most major airlines have resumed service but cautioned passengers that disruptions could last throughout the day.

Also, numerous police departments across the U.S. have reported that the outage affected their 911 service and encouraged people to use non-emergency lines if they could not reach 911 directly.

The outage was linked to cybersecurity firm CrowdStrike. The company's CEO said the outage was not due to a security incident.

"CrowdStrike is actively working with customers impacted by a defect found in a single content update for Windows hosts. Mac and Linux hosts are not impacted. This is not a security incident or cyberattack," CrowdStrike CEO George Kurtz said earlier in the day. "The issue has been identified, isolated and a fix has been deployed ... Our team is fully mobilized to ensure the security and stability of CrowdStrike customers."

Microsoft 365 said midday Friday that services have returned to normal.

"Yesterday, CrowdStrike released an update that began impacting IT systems globally. We are aware of this issue and are working closely with CrowdStrike and across the industry to provide customers technical guidance and support to safely bring their systems back online," Satya Nadella, Microsoft CEO, said.

The U.S. Department of Homeland Security released a statement Friday morning.

"The Department, and the Cybersecurity and Infrastructure Security Agency are working with CrowdStrike, Microsoft and our federal, state, local and critical infrastructure partners to fully assess and address system outages," the department said.