Heathrow Shutdown Shows How Airline and Airport Chaos Can Quickly Spiral

The airline industry prepares for chaos. But that doesn’t make responding to it any less complicated.

Carriers were working frantically on Friday to reroute flights after a power outage at Heathrow Airport in London, a global hub, left tens of thousands of passengers stranded. But the aviation system is deeply interconnected, and responding to such severe disruptions is a delicate balancing act. For airlines, moving even a small number of flights can have cascading effects.

“They’re thinking not just in terms of a single day, but recovery,” said Dr. Michael McCormick, a professor of air traffic management at Embry‑Riddle Aeronautical University, who managed the federal airspace over New York during the Sept. 11 terrorist attacks. “They have to look at where passengers with bags, aircraft and aircrews need to be tomorrow, the next day, and the next day.”

When crises occur, airlines’ network operation centers jump into overdrive. They are the nerve centers of the business — typically large, quiet, secure rooms with power backups and protections against severe weather and disasters.

At large airlines, the operations centers are staffed around the clock with teams that monitor the weather, manage planes and flights, communicate with air traffic control, schedule crews and much more.

Small disruptions can be handled surgically — a sick pilot can be replaced with an alternate on call nearby or a broken plane swapped out for another. But bigger disruptions like the one at Heathrow can require scrapping and reworking intricate plans while taking into account a wide range of limitations.

When Southwest Airlines struggled to overcome the effects of severe weather during the winter holidays in late 2022, for example, it canceled thousands of flights over several days in order to move crews and planes to where they needed to be.

On Friday, the budget airline Ryanair, which operates frequent flights across Europe, said it had added eight flights between Dublin and London’s Stansted airport over two days to “rescue” passengers affected by the Heathrow outage. Other airlines were also working desperately to reroute passengers, but that is often easier said than done.

Planes differ in how many people they can carry and how far they can fly, so a small plane used for shorter domestic flights cannot easily be swapped for a larger one used on longer flights. They also must be fueled adequately and their weight balanced appropriately, needs that have to be adjusted if planes are rerouted.

Regulations also require that pilots and flight attendants are not overworked and are allowed to rest after a certain number of hours on the clock. If a flight takes too long to depart, a crew can time out. When schedulers reassign crews, they also have to take into account where those pilots and flight attendants are needed next, or they could risk more disruptions later.

“Even if things do get back up and running soon, we will have the logistical issue of getting new crews out to operate those aircraft,” Sean Doyle, the chief executive of British Airways, said in a video statement.

The airline operates more than half the flights into and out of Heathrow, according to Cirium, an aviation data firm. In the statement, Mr. Doyle said the outage would have “a huge impact” on British Airways customers in the following days.

Airlines, of course, do not operate in isolation. As they change plans, they need to work with airport and air traffic control officials who may have limited resources to accommodate the changes. Airports are limited not just in how many flights they can receive, but also, in some cases, what types of planes they can safely accept. National aviation systems may also be limited: In the United States, for example, many air traffic control towers have long suffered from controller shortages.

Disruptions, referred to as irregular operations, are frequent and the industry prepares for them. Airlines and airports rehearse how they might respond to disarray caused by severe weather, terrorist attacks and other catastrophes and maintain crisis response playbooks. But disorder can take many forms, so those plans are often only guides.

“There is always a need for some improvisation as every situation has its own unique challenges,” said Tom Parry, the head of business resilience at Kiwi.com, a travel search and deals website.

The power outage at Heathrow was caused by a fire at a nearby electrical substation. The police in London said that there was no indication that it was the result of an intentional act, though they were still investigating. Such fires are rare, but some criticized Heathrow for not being better prepared.

“How is it that critical infrastructure — of national and global importance — is totally dependent on a single power source without an alternative,” Willie Walsh, director general of the International Air Transport Association, a global airline trade association, said in a statement.