PTI Houston

More than 800 United Airlines flights were cancelled and hundreds more delayed by late Wednesday following a major technology outage that forced a systemwide ground stop across the United States, severely disrupting both domestic and international travel.

At Houston's George Bush Intercontinental Airport (IAH), where United operates a key hub, long lines and frustrated passengers filled terminals. The airline traced the outage to failures in its dispatch and fuelling systems. "Due to a technology issue, we are holding United mainline flights at their departure airports," United said in a statement. "We expect additional flight delays this evening as we work through this issue."