By David Shepardson
WASHINGTON (Reuters) - United Airlines said it has ended an hour-long nationwide ground stop after a software update caused a widespread slowdown in United's technology systems.
The Chicago-based air carrier said it is "investigating the cause, but it was not a cybersecurity issue."
The issue did not impact flights that were already airborne and were able to continue to destinations as planned.
The Federal Aviation Administration (FAA) said earlier it had issued the ground stop at United's request. According to FAA records and United, the ground stop lasted just over an hour and was ended around 1:45 p.m. EDT (1745 GMT).
FlightAware, a flight tracking website, said United had canceled seven flights and delayed 364 flights, or 13% of its flights on Tuesday.
Airline ground stops because of computer issues are uncommon but not unprecedented. In April, Southwest Airlines said a technology failure caused a one-hour nationwide stoppage of its flights.
United shares closed down 2.6%.
(Reporting by David Shepardson and Rami Ayyub; Editing by Doina Chiacu, Jonathan Oatis, Nick Zieminski and Sandra Maler)