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Getty Images<\/span><\/div>\n<\/div>\nHeathrow Airport was shut down and thousands of homes were left without power on Friday after a fire at a nearby electric supply substation.<\/p>\n More than 1,300 flights have been cancelled, passengers are being told not to travel to the airport, and more than 150 people have been moved out of their homes.<\/p>\n So what do we know about what went wrong?<\/p>\n<\/div>\n A fire at North Hyde substation in Hayes, west London, caused the outage. <\/p>\n Firefighters were called at 23.23 GMT on Thursday and the fire was under control by 06:28 on Friday.<\/p>\n The cause of the fire is not yet known. Counter terrorism police are leading an investigation looking into whether there was any foul play.<\/p>\n<\/div>\n It is not yet clear why a fire at one substation shut down Heathrow, the UK’s busiest airport, completely.<\/p>\n The airport had multiple sources of power but the fire had affected a “particularly important bit,” a National Grid source told the BBC.<\/p>\n The substation’s back-up generator also appeared to have been “knocked out,” Energy Secretary Ed Miliband said.<\/p>\n Heathrow appears to have been reliant on one critical component and the National Grid distribution network was not set up to supply sufficient electricity in this situation.<\/p>\n A Heathrow source said these questions would be investigated, but at present, all of the airport’s efforts were directed towards reopening safely.<\/p>\n A source who designs data centres, which require a similar amount of electricity to Heathrow, told the BBC data centres have two supplies from the National Grid and stand-by generators.<\/p>\n They also have batteries to cover electricity needs until the generators can start.<\/p>\n Willie Walsh, the director general of the International Air Transport Association, which represents airlines, said the outage raised “serious questions”.<\/p>\n “Firstly, how is it that critical infrastructure – of national and global importance – is totally dependent on a single power source without an alternative? If that is the case – as it seems – then it is a clear planning failure by the airport,” he said.<\/p>\n<\/div>\n The airport has back-up power for certain systems, but kickstarting alternative power supplies for the whole airport takes time, and the systems need to be checked to ensure they are working properly.<\/p>\n Heathrow uses as much energy as a small city, so it is not possible for it to have the back-up power by itself to run its operation safely.<\/p>\n A Heathrow source said its back up diesel generators and uninterruptable power supplies in place all operated as expected.<\/p>\n The problem lay with the National Grid, the source said, pointing out thousands of homes had been left without power, not just the airport.<\/p>\n There are two National Grid substations close to Heathrow: one at North Hyde, north of the airport, and one at Laleham, south of the airport, according to energy analysis firm Montel Group.<\/p>\n It appears that only the North Hyde substation is connected to Heathrow through the local distribution network, says Phil Hewitt, director at the firm.<\/p>\n Although Heathrow has its own biomass combined heat and power plant, it seems that couldn’t provide full back-up capacity.<\/p>\n “This potential lack of resilience at a critical national and international infrastructure site is worrying,” said Mr Hewitt. “An airport as large and as important as Heathrow should not be vulnerable to a single point of failure.”<\/p>\n Robin Potter, a research fellow at Chatham House, said Heathrow was one of only two UK airports \u2013 Gatwick is the other \u2013 that has any level of regulation around its resilience standards.<\/p>\n “These are actually the better airports in the UK for how their resilience is assessed and regulated,” he said.<\/p>\n In 2023, the National Infrastructure Commission recommended to the government that it should set standards for some key sectors of infrastructure such as telecoms, water, transport and energy by 2025.<\/p>\n It followed up with a further report at the end of last year detailing how the government could do that for those sectors. <\/p>\n “Those have effectively been on the government’s desk since October 2023,” he said.<\/p>\n<\/div>\n Power should be back on “in hours” but it was too soon to say exactly when, a National Grid source said.<\/p>\n However, Heathrow said it didn’t have any “clarity on when power may be reliably restored”.<\/p>\n There will be “significant disruption over the coming days and passengers should not travel to the airport under any circumstances until the airport reopens”.<\/p>\n “We know this will be disappointing for passengers and we want to reassure [them] that we are working as hard as possible to resolve the situation,” it said.<\/p>\n<\/div>\nWhat caused the outage?<\/h2>\n<\/p>\n
Does Heathrow have back-up systems?<\/h2>\n<\/p>\n
Why hasn’t the outage been fixed yet?<\/h2>\n<\/p>\n
When will the situation be resolved?<\/h2>\n<\/p>\n