All United Airlines flights were grounded nationally Wednesday morning due to a "connectivity issue" before the ground stop was lifted 30 minutes later.
The Federal Aviation Administration issued the stop at the company's request across the U.S. and Canada between 1 a.m. and 2:30 a.m. ET — but it was canceled at 1:30 a.m.
The reason given by the Air Traffic Control System Command Center was simply "COMPANY REQUEST / TECHNOLOGY."
The airline told NBC News in an email: "United experienced a brief connectivity issue just before midnight Central time on Tuesday, but has since resumed normal operations."
FlightAware's "Misery Map" of delays across the country showed 42 delays and four cancellations between 12 a.m. and 4 a.m. ET with Los Angeles International Airport the worst affected.
The airline had a similar outage in August, when airports in Chicago, San Francisco, Houston and Newark, New Jersey, were hit by delays due to an unspecified problem.
