Britain's Heathrow said it had begun the process of reopening on Friday after a fire knocked out its power supply and shut Europe's busiest airport for the day, stranding thousands of passengers and causing travel turmoil worldwide.
Heathrow, the world's fifth-busiest airport, was forced to close after a huge fire engulfed a substation near the airport on Thursday night.
"Our teams have worked tirelessly since the incident to ensure a speedy recovery. We’re now safely able to restart flights, prioritizing repatriation and relocation of aircraft," the airport said in a statement on X.
"We hope to run a full operation tomorrow and will provide further information shortly. Our priority remains the safety of our passengers and those working at the airport. We apologize for the inconvenience caused by this incident."
The closure not only caused misery for travelers but provoked anger from airlines who questioned how such crucial infrastructure could fail.
The industry is now facing the prospect of a financial hit costing tens of millions of pounds, and a likely fight over who should pay.
"You would think they would have significant back-up power," one top executive from a European airline told Reuters.
Police said that while there was no indication of foul play, they retained an open mind and counter-terrorism officers would lead the inquiries, given their capabilities and the critical nature of the infrastructure.
Airline experts said the last time European airports experienced disruption on such a large scale was the 2010 Icelandic ash cloud that grounded some 100,000 flights.