Computer glitch grounds United flights, passengers

SAN FRANCISCO (KGO) -- United Airlines flights are back in the sky after worldwide ground stop Wednesday morning caused by a system glitch. It impacted hundreds of passengers who were stuck waiting at SFO.

"When we came in, we could barely get into the door because the lines were so long," said Treg Campbell, a United passenger at SFO.

Passengers remained calm through the delays but frustrated they weren't given any information by United Airlines employees.

Many say updates were coming from social media, news websites and word of mouth.

"I definitely am not pleased," said passenger Molly Tuvesom..

Many say updates were coming from social media, news websites and word of mouth.

United Airlines says a network connectivity issue caused the backup. Specifically, it was an issue with a router, according to a United Airlines Spokesperson.

The issue impacted the ability to communicate data to aircrafts on the ground. That's why the Federal Aviation Administration grounded all flights.

United says flights in the air were not directly affected.

The boards at SFO were filled with delays.

Once the network connectivity issue was resolved, ticket agents diligently worked to get passengers on their way. In some cases, they even hold flights -

Many passengers worrying they'd miss connecting flight, like Tuvesom. "We're going to Venice, Italy," she said.

United says the issue was not a cyber attack or due to hacking.

In a statement, United said: "We are recovering from a network connectivity issue this morning and restoring regular flight operations. We have a waiver available at United.com for customers who are able to change their flight plans."