United Says IT Outage Resolved, Dozen Flights Canceled Monday

United Airlines expected minimal impact to its operations Monday from a major system outage the previous day, which grounded its domestic flights for hours.

An IT issue prevented United pilots from getting aircraft weight and balance information pre-takeoff, leading the airline to request that the Federal Aviation Administration issue a ground stop for its flights. The outage affected more than 200 flights.

A United spokesperson did not say what exactly had caused the outage, describing the cause vaguely as “an IT issue” in a statement emailed Monday. The airline cancelled about a dozen of the 4,500 flights scheduled for Monday and expected a “small number” of short delays.

It issued a ground stop for all domestic mainline flights at 5:30 pm Central. The issue was resolved and flights started resuming 2.5 hours later, the spokesperson said, adding:

Legacy IT Industry-Wide Issue

Outdated legacy IT systems are an industry-wide problem for airlines, and upgrades are extremely difficult because the systems have to keep running around the clock. The networks are very complex, having grown over decades, but big and expensive overhauls are needed, Bob Edwards, United’s former CIO, told Bloomberg last August, following a Delta Airlines system meltdown that grounded flights globally.

That outage, caused by an electrical-equipment failure, cost Delta $150 million. As the incident demonstrated, technical glitches can be extremely costly for airlines, which have to issue refunds to customers whose flights are cancelled or delayed as a result.

Read more: Delta: Data Center Outage Cost Us $150M

Edwards retired in 2014 under pressure that followed several disruptions at United, according to Bloomberg. “I don’t believe the flight ops, maintenance, passenger service systems, crew and dispatch applications are engineered with the level of redundancy needed,” he said in an interview with the news service last year. “Mistakes will happen, devices will malfunction.”

In 2015, another United system outage, caused by a network connectivity issue, disrupted customer ticketing and the airline’s ability to dispatch crews.

Answering a question from an analyst about its passenger reservation system on a recent earnings call, United president, Scott Kirby, said the system was fully operational and ruled out switching onto a different system.

The United spokesperson did not answer a question from DCK about the airline's plans for preventing IT outages in the future.