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Investigators combed through the burned-out remains of a power substation near London\u2019s Heathrow Airport on Friday, seeking the cause of a spectacular blaze that shuttered Europe\u2019s busiest travel hub for much of a day and raised broader questions about Britain\u2019s energy infrastructure.<\/p>\n
Officials and energy experts said a fault in a transformer with 275,000 volts running through it probably sparked a massive, oil-fueled fire that severed the airport and tens of thousands of nearby homes from the power grid. Systems designed to prevent such a fire apparently failed, and the size of the blaze appeared to keep a second, nearby transformer from restoring electricity.<\/p>\n
But the mystery of what caused that fault in the first place remained far from solved by the end of the day on Friday, even as flights resumed at Heathrow.<\/p>\n
The Metropolitan Police in London said that counterterrorism specialists had taken charge of the investigation, \u201cgiven the location of the substation and the impact this incident has had on critical national infrastructure.\u201d At the same time, political leaders and industry experts said it appeared most likely that the fire was an accident.<\/p>\n<\/div>\n<\/div>\n
Both possibilities left residents of Britain and global travelers rattled.<\/p>\n
If a malicious adversary can so dramatically disrupt worldwide travel by causing a fire in a neighborhood power station, it raises new concerns about the ability of open societies like Britain\u2019s to guard against such nontraditional attacks.<\/p>\n
And if the fire was the result of an undetected weakness in the basic infrastructure of Britain\u2019s power grid, the scope of the chaos that was unleashed could undermine confidence in the nation’s ability to fix crumbling systems at a time when finances are already strained.<\/p>\n<\/div>\n<\/div>\n
Prime Minister Keir Starmer and Sadiq Khan, the mayor of London, sought to reassure residents and travelers on Friday, with Mr. Khan telling Sky News in an interview that despite the involvement of counterterrorism officers in the investigation, there was \u201cno reason at all for anyone to be concerned or alarmed.\u201d<\/p>\n
Still, neither the prime minister nor the mayor offered answers to some of the urgent questions being asked by frustrated travelers, nervous neighbors of the airport and political officials across the country.<\/p>\n<\/div>\n<\/div>\n
Why didn\u2019t the airport have sufficient power backups? Did the electric utility not plan for the possibility of such a fire, either from sabotage or technical malfunction? Do major airports usually have backup systems that can power the entire operation, or do they rely on one main source of energy?<\/p>\n
John McDonnell, a lawmaker who represents Hayes, the area where the fire broke out, said that any investigation undertaken in the days ahead would need to look at \u201cwhy backup arrangements have not worked.\u201d<\/p>\n
\u201cThere are lessons that have got to be learned here,\u201d he told reporters on Friday afternoon.<\/p>\n
By early afternoon on Friday, Britain\u2019s National Grid said the network of the North Hyde substation, where the fire happened, had been reconfigured to restore power to the airport and neighborhood, calling it an \u201cinterim solution\u201d while repairs get underway. Officials with National Grid did not respond to an email requesting information about the incident.<\/p>\n<\/div>\n<\/div>\n
That announcement paved the way for a partial opening of the airport, where the first flights began landing again by the evening.<\/p>\n<\/div>\n<\/div>\n
\u201cWe will now work with the airlines on repatriating the passengers who were diverted to other airports in Europe,\u201d airport officials said in a statement. \u201cWe hope to run a full operation tomorrow.\u201d<\/p>\n
But even as Heathrow attempts to return to normal operations, a sense of uncertainty remains.<\/p>\n
Ed Miliband, Britain\u2019s energy secretary, said in an interview early on Friday with Sky News that the fire at the electrical substation that crippled Heathrow Airport also took out at least one of the main backup systems designed to keep the power running.<\/p>\n
\u201cThere was a backup generator, but that was also affected by the fire, which gives a sense of how unusual, unprecedented it was,\u201d Mr. Miliband said.<\/p>\n
Transformers convert current from one voltage to another, and are often filled with oil that acts as both an insulator and a coolant. The types of oil used can withstand high temperatures, but they can ignite if they get hot enough.<\/p>\n
In the case of the transformer near Heathrow, experts said it would have been turning 275,000 volts into 66,000 volts when it apparently failed. Jonathan Smith, the deputy commissioner for the London Fire Brigade, said the blaze involved \u201ca transformer comprising 25,000 liters of cooling oil that was fully alight\u201d at the substation.<\/p>\n<\/div>\n<\/div>\n
The failure of at least one backup system to quickly restore power after such a major outage is likely to be at the center of questions about the reliability of Britain\u2019s infrastructure in the aftermath of the fire and airport closure.<\/p>\n
Britain\u2019s National Infrastructure Commission, which makes recommendations to the government on major infrastructure, said that the fire had underscored the need for better preparedness for shocks, and for operators to build resilience into their systems and conduct regular stress testing.<\/p>\n
\u201cWe\u2019ve been clear the U.K. needs national resilience standards for our transport, digital, energy and water infrastructure,\u201d said the commission\u2019s chair, John Armitt, in a statement. \u201cThese will give clarity to operators and users about what levels of service they should expect in the face of short- and long-term disruptions, and ensure regulators have a clear yardstick against which they can ensure sufficient investment in resilience is made.\u201d<\/p>\n