Heathrow executives are defending their response to a fire that shut down Europe’s busiest air hub for almost a day.

Heathrow’s chief executive has defended the airport’s response to the power outage and shutdown that sparked global travel chaos, apologizing to stranded passengers and confirming the airport is “operating as normal” Saturday.

London's Heathrow Airport​, one of the busiest airports in the world, was shut down by a power outage caused by a fire at an electrical substation.

It has been a difficult week for Europe’s busiest airport. Friday’s power failure exposed flaws in Heathrow’s resilience, contingency planning and potential vulnerability to sabotage, as well as its ownership and investment structures (it is largely controlled by interests foreign and loaded with debt).

British police said a fire which caused Heathrow Airport to close for 18 hours last week was no longer being treated as a potentially criminal matter.Heathrow, Europe's busiest airport, shut on Friday after a fire at a nearby substation cut its power supply,

There is no evidence to suggest the substation fire that shut down Heathrow airport was suspicious, police say. The fire, which broke out in Hayes on Friday, resulted in the closure of Britain's busiest airport for a day.