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It took Heathrow Airport more than seven hours to restart its flight after power was restored after the fire six weeks ago.
Europe’s busiest airport closed just after 1am on Friday, March 21st. A fire at a nearby electrical substation caused a widespread power outage as it was supplied to the airport.
According to an interim report released Thursday by the UK government’s national energy system operator, power had been restored to all terminals in Heathrow by 10:56am on Friday, and its internal network was fully revitalized.
One flight with the crew landed around 6pm after the airport completed its safety check. The airport did not reopen until Saturday.
“Before you arrive at the airport, make sure your safety critical system is fully operational,” the report said.
The airport previously said that power needs to be restored across the site before it can resume, including critical systems outside the terminal.
Heathrow’s chief executive Thomas Woldbye told MPS last month that the internal review would consider whether the airport could reopen some terminals more quickly. The airline says it believes that at least Terminal 5, the British Airways home, could reopen sooner.
An airline executive said Thursday’s report raised more questions about how long it took to resume operations.
Power sources have been cut to almost 67,000 homes and businesses as well as airports. By 1am on Friday, about 42,000 homes and businesses had been reconnected, with all domestic customers reconnecting just after noon, the report said.
The interim report details the fire at the substation, but said the underlying cause is not yet known. The final report, scheduled for the end of June, may provide details on the cause of the flames. Metropolitan Police said they previously discovered there was no evidence to suggest that it was suspicious.
The Northhide electrical site, owned by National Grid, in West London, has three transformers, including one designed for backup, located more than 30 meters away from the other two, the report says.
The fire was fixed with cooling oil inside one of the transformers and automatically cut off. The backup transformer remained designed first, so the two transformers worked and no longer had a disruption in supply.
However, according to the report, the second transformer was automatically disconnected after 28 minutes due to the “protective system.” The backup transformer was also cut off because it was connected to the same circuit.
The disruption caused by the fire at the substation has sparked extensive questions about the resilience of the UK’s important national infrastructure.
The National Energy System operator said he hopes to develop recommendations in the final report covering energy infrastructure resilience, site design, “asset health assessments” and “sector incident management.”
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Heathrow said the report raised “important questions” about National Grid and distribution system operator SSEN.
“To make it even more clear how the fire started and why the two transformers were affected afterwards will help ensure the UK’s energy grid have greater resilience to move forward.”
Energy Secretary Ed Miliband said his department will “wait a full report to understand what happened, to learn lessons to strengthen the UK’s energy resilience and protect our critical national infrastructure.”
