Southwest Airlines forced to ground all US flights - again

Southwest Airlines experienced a major technical issue Tuesday morning, forcing the US carrier to ground all flights nationwide and causing flight delays for thousands of passengers – its second nationwide grounding since the airline's infamous December holiday breakdown.

According to the US Federal Aviation Administration (FAA), Southwest had requested the grounding after “experiencing a computer technical issue with one of their systems,” around 10.30 am EST Tuesday.

About an hour after the grounding was implemented, the FAA announced the low-cost airline was back in business, but not before roughly 43% of its flights were reported delayed.

The technical issue apparently was caused by a firewall failure, the airline announced.

“Southwest has resumed operations after temporarily pausing flight activity this morning to work through data-connection issues resulting from a firewall failure," the budget airline said.

“Early this morning, a vendor-supplied firewall went down and connection to some operational data was unexpectedly lost.”

FlightAware, the flight-tracking website, showed a total of 1,820 Southwest Air flights were delayed by Tuesday afternoon. No flights have been reported canceled, although that was expected to change throughout the day.

Southwest said it “worked quickly to minimize flight disruptions.”

It's the second major operational breakdown caused by a technical glitch in Southwest’s aging infrastructure in the past six months.

Last December, a faulty router took the airline’s reservation system offline during Christmas Eve and New Year's Day, one of the busiest holiday travel weeks of the year.

The budget airline’s system-wide breakdown caused more than 60% of Southwest flights to be canceled, and left thousands of passengers stranded during the holiday rush.

The estimated 16,700 flight cancellations during that failure have cost Southwest more than $1 billion so far.

The company is also facing two separate class-action lawsuits filed by Southwest shareholders and passengers in the aftermath of December’s breakdown.

The shareholder suit accuses the airline and three of its top brass of willfully ignoring “serious risks” associated with its outdated technology infrastructure and support systems.

The passengers suit claims the airline denied refunds for their canceled flights.

Southwest is the third largest carrier in the US and headquartered in Dallas, Texas.

Travelers are being asked to check flight status on Southwest.com