Xcel Energy identifies cause of Denver International Airport power outage that trapped passengers, disrupted flights
A single malfunctioning piece of new equipment triggered last month's sweeping power outage at Denver International Airport — an incident that stranded passengers in elevators and delayed nearly 500 flights.
Xcel Energy confirmed Tuesday that the March 18 blackout occurred as crews were energizing a new transformer at a substation when the equipment failed.
"This isn't a minor inconvenience," said airport spokesperson Stacey Stegman. "This was a significant power outage that impacted the airport."
An internal airport "after action" report, obtained by CBS News Colorado through open records laws, paints a picture of widespread disruption.
"The campus-wide power outage resulted in significant operational disruptions across the airport, with several major systems affected," the report states.
Among the hardest-hit systems: jet bridges, gate operations, ramp control towers, and the airport train network. Eight passengers were trapped in elevators for periods ranging from eight to 19 minutes, according to the two-page document.
The outage also impacted Wi-Fi and internal communications.
"So some passengers were being diverted to areas that made no sense," Stegman said.
A Morning of Chaos
According to the report's timeline, power went out at 9:21 a.m. The Federal Aviation Administration issued a ground stop less than an hour later, at 10:10 a.m.
By the time the situation stabilized, 477 flights had been delayed and nine canceled.
Videos posted on social media showed thousands of travelers waiting in crowded conditions as airport trains gradually came back online.
Partial power was restored after about 40 minutes, but it took roughly two-and-a-half hours to fully restore electricity across the airport.
"This is something beyond our control," Stegman said. "This wasn't an incident the airport caused or a problem with our trains."
Communication Breakdowns
The report also highlights a major challenge: keeping passengers informed in real time.
"Providing timely and accurate information to passengers was challenging as there were some mixed messages coming from different groups," the report notes.
Stegman said internal communication systems, including radios, were affected, leading to what she described as a "fair amount of confusion."
In response, DIA plans to upgrade its communications infrastructure and improve how quickly buses can be deployed during emergencies.
"We're definitely going to be looking at our communication systems and is there a better way to communicate with passengers," she said.
Fixes -- and Future Investment
Xcel Energy says it is already addressing the root cause.
Xcel spokesperson Lisa Andersen told CBS Colorado the company is "working with the manufacturer to fix the equipment piece and get the new transformer in service."
She added that Xcel plans to invest nearly $118 million over the next five years to support DIA's growing energy demands, including building two new substations.
"We are actively working with city officials to ensure all energy needs are met now and for years to come," Andersen said.
Stegman told CBS Colorado that DIA is Xcel's largest customer in Colorado.
Not the First Outage
While March's outage was blamed on faulty equipment, a previous disruption had a far more unusual cause.
According to an after action report on an Aug. 22, 2025 outage, that "brief power interruption" was traced back to a snake.
Xcel determined the animal had "contacted an energized fuse, creating the short that led to the outage."
