CNN
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All flights on several major U.S. airlines, including Delta Air Lines, United Airlines and American Airlines, were grounded Friday morning due to communications issues, according to the Federal Aviation Administration.
The grounding affects all of the airline’s flights, regardless of destination, the FAA said.
It’s unclear how long the grounding will last, but the FAA indicated an update would be provided by 5 a.m. ET.
The Frontier Airlines suspension comes after a major Microsoft outage caused the airline to halt flights for several hours on Thursday, though both airlines have since lifted the suspension.
Frontier Airlines said it was affected by a systems outage early Thursday and offered refunds to passengers who were inconvenienced.
Other competitors, including Allegiant and Sun Country, also said they were having difficulty with online booking, check-in and trip management features.
The FAA also announced the suspension of all Allegiant Air flights Friday morning.
Microsoft said on its Azure Cloud Software Status Report site that some customers in the central US experienced an outage at around 6pm ET, “causing disruptions to service management operations and connectivity or service availability.”
The company said it had identified the cause and was working to resolve it. A company spokesman did not immediately respond to a request for comment.
A number of international airlines, including Virgin Australia and Qantas, also reported technical glitches at airports in Europe and the Asia-Pacific region on Friday.