Heathrow airport should not be marking its own homework on energy network resilience

Ten hours to restart! The core question is why Heathrow was happy to tolerate such a timetable in its emergency planning

- Nils Pratley

We purchase and pay for a resilient setup from our suppliers," Thomas Woldbye, Heathrow's under-pressure chief executive, told the transport select committee, adding that the airport racked up energy costs of £135m a year. "Are we then also supposed to have a setup next to it? And then we would have to have a whole power station at the cost of billions to the airlines." So runs Heathrow's case that there was no alternative to closing the airport for a full day last month after a fire knocked out a National Grid substation, one of three serving the airport.

Heathrow's engineers had to reconfigure an internal grid to take electricity solely from the other two substations. The reconfiguration involved shutting down and restarting 1,000 systems and could not be done in less than 10 hours. Therefore passengers had to be told to stay away during the process. Any other approach would have been unsafe.