Problem Arose In System By Which Aircraft Send Information To United Operations

All United Airlines Flights were grounded for a time Sunday night due to a system-wide IT issue, according to the company.

CNN reports that the carrier announced the problem in a Tweet at 8:06 EST Sunday night. "A ground stop is in place for domestic flights due to an IT issue. We’re working on a resolution. We apologize for the inconvenience," the message said.

Sources familiar with the situation said that the problem cropped up in a communications the carriers ACARS system, by which aircraft send information to United Operations. ACARS records and reports such information as departure times and weight and balance.

The outage only affected flights that were waiting to depart. Aircraft already en route were in no danger, according to the report, and it also did not affect communications with ATC.

The backup to ACARS is to input the information by hand. One source said the ground stop was put in place as a precautionary measure.

The ground stop lasted about an hour. United Tweeted at 9:07 pm that "The ground stop has been lifted. We’re working to get flights on their way. We apologize for the inconvenience to our customers."

(Image from file)

FMI: www.united.com