Unlock the Editor’s Digest for free
Roula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter.
Heathrow airport took more than seven hours to restart flights after power was restored following a fire six weeks ago, according to an interim report that admitted the cause of the blaze was still unknown.
Europe’s busiest airport shut down shortly after 1am on Friday, March 21, after a fire at a nearby electricity substation feeding the airport led to widespread power cuts.
Power was restored to all of Heathrow’s terminals by 10.56am on Friday and its internal network fully re-energised by 2.23pm, according to the interim report published on Thursday by the UK government’s National Energy System Operator.
One flight with crew members landed around 6pm, after the airport had completed safety checks. The airport did not reopen fully until Saturday.
“There was a period of safety checking to . . . ensure safety critical systems were fully operational prior to passengers arriving at the airport,” the report said.
The airport has previously said that it needed power restored across its site, including critical systems outside its terminals, before it could reopen.
Thomas Woldbye, Heathrow’s chief executive, told MPs last month that an internal review would consider whether the airport could have reopened some terminals more quickly. Airlines have said they believe that at least Terminal 5, the home of British Airways, could have reopened sooner.
One airline executive said Thursday’s report raised further questions about how long it took to restart operations.
Power supplies were cut to almost 67,000 homes and businesses as well as the airport. About 42,000 homes and businesses were reconnected before 1am on Friday, and all domestic customers by shortly after midday, the report said.
The interim report laid out details about the fire at the substation, but said the root cause was not yet known. The final report, which is due by the end of June, may lay out further details about the cause of the blaze. The Metropolitan Police has previously said it found no evidence to suggest it was suspicious.
The electrical site in North Hyde, west London, owned by National Grid, had three transformers, including one designed for backup and positioned more than 30 metres away from the other two, the report said.
The fire took hold in cooling oil inside one of the transformers, causing it to automatically disconnect. The backup transformer initially kicked in as designed, leaving two transformers working and no interruption of supply.
But, according to the report, the second transformer automatically disconnected 28 minutes later due to “protection systems”. This cut off the backup transformer as well, because it was connected to the same circuit.
The disruption caused by the substation fire has triggered widespread questions about the resilience of the UK’s critical national infrastructure.
The National Energy System Operator said it expects to make recommendations in its final report covering the resilience of energy infrastructure, site design and “assessments of asset health” as well as “cross-sector incident management”.
Heathrow said the report raised “important questions” for National Grid and the distribution system operator, SSEN.
It added: “Further clarity on how the fire started and why two transformers were subsequently impacted can help ensure greater resilience for the UK’s energy grid moving forward.”
Ed Miliband, the energy secretary, said his department would “await the full report to understand what happened and learn lessons to strengthen UK energy resilience and protect our critical national infrastructure”.
