Airlines rely on complex systems: Why the CrowdStrike hiccup could cause days of chaos

Thousands of flights were canceled and delayed across the country Friday as a Microsoft system outage took down the backend IT system at many airlines.

According to cyber security firm CrowdStrike, an update to its software affected Microsoft’s Windows operating system, which many airlines rely on for reservations, flight scheduling and other functions.

"Any time new software is deployed, there is the potential for bugs or errors to affect the operating system that is currently in use," Tim Ehrenkaufer, assistant professor of aeronautical science at Embry-Riddle Aeronautical University, said in an email to USA TODAY. "Ultimately, events like these serve as valuable reminders for organizations to always back up their data, in the case that a rollback is required. With technology, there’s always the likelihood of a glitch and, usually, these types of mishaps are resolved quickly and without any major or long-lasting effects."

Which systems were affected?

The CrowdStrike outage seemed to mostly affect airlines’ reservations and scheduling systems.

The aviation industry relies on a series of overlapping technologies, from flight control software in the cockpit to tracking software in Federal Aviation Administration control towers.

The FAA and most airports did not report outages in their systems, and airlines did not hint at any issues related to flight controls. Nonetheless, all these systems need to work in tandem to keep planes moving in sequence and on schedule.

The FAA issued ground stops for several carriers at the airlines' request, meaning those operators were required to pause departures while the outage was addressed, according to the agency .

What happened to flights in the air?

Flights in the air did not seem to be affected by the outage, which mainly appeared to impact airline IT systems on the ground. However, a single system outage typically has a knock-on effect in aviation.

“Take a big airline like one of the big four; they often have different IT systems for crew scheduling, for aircraft maintenance, reservations, it’s endless,” William J. McGee, senior fellow for aviation and travel at the American Economic Liberties Project, told USA TODAY. “I don’t think the average passenger understands it’s not like there’s one big system that’s running everything. It’s multiple systems, and it only takes one to knock it out.”

What should affected passengers know?

Airlines will likely take some time – maybe days – to fully recover.

When Southwest Airlines had an IT meltdown over the 2022-2023 winter holidays, their operations took nearly 10 days to fully normalize.

“A thunderstorm that lasts 15 minutes can cancel flights for 12 hours,” McGee said. “I hope things get cleared up quickly, but I would warn travelers that they should expect residual effects from this, assuming things go well and that we don’t have a second episode, the effects from this could easily run through Sunday.”

For travelers whose plans are affected, many airlines issued waivers to allow them to rebook flights for later travel dates. The Department of Transportation also classified the impacts of Friday’s outage as “controllable” by airlines, which means that the carriers are on the hook for honoring their customer service commitments .

Pilot concerns

The Air Line Pilots Association has long maintained that technology is no replacement for human experience in aviation. The association said Friday’s meltdown shows that aviation isn’t ready to reduce the number of pilots required on commercial flights or move to fully autonomous operations, as some advocates have suggested.

“Today’s global outage is a reminder that despite advances in technology, operational systems – especially in aviation – must have redundancy. That’s why the most important safety feature on every airline flight will always be two well-trained and rested pilots on the flightdeck,” ALPA President Capt. Jason Ambrosi said in a statement. “Relying exclusively on technology and automation and removing pilots from the flightdeck, as some are suggesting, is a step too far. Technological advancements can help improve aviation safety but can never be a substitute for the pilots on an aircraft.”

Zach Wichter is a travel reporter for USA TODAY based in New York. You can reach him at zwichter@usatoday.com.

This article originally appeared on USA TODAY: Airlines rely on complex systems: Why the CrowdStrike hiccup could cause days of chaos