Heathrow: Airport shutdown motive nonetheless unknown, file says

The root motive of a hearth which resulted in the shutdown of Heathrow Airport and affected masses of hundreds of trips international “remains unknown”, an meantime file says.

Heathrow used to be closed to all flights for a lot of 21 March after a fireplace at a close-by electric substation, which began the former evening, brought about an influence outage on the airport.

In Thursday’s file, the National Energy System Operator (Neso) mentioned a transformer disconnected and stuck fireplace on the substation in Hayes, west London.

The grid operator’s ultimate file is due via the tip of June. Heathrow Airport mentioned it welcomed the meantime findings and that it was hoping the overall file would supply solutions on what brought about the hearth.

The Metropolitan Police’s counter-terrorism unit performed an preliminary investigation into the hearth, however Neso famous that detectives discovered there “no evidence to suggest” the incident used to be suspicious.

The energy outage and next closure of Heathrow resulted in greater than 270,000 trips being affected.

Energy Secretary Ed Miliband in a while after ordered an pressing investigation into the hearth to forestall it “from ever happening again”, and advised Neso to offer its preliminary findings inside of six weeks.

Heathrow’s control has been criticised for the verdict to near the airport and the lengthy shutdown that adopted.

Neso mentioned energy used to be restored to Heathrow’s terminals seven hours earlier than flights resumed.

In an in depth timeline, it mentioned the hearth on the North Hyde substation began at 23:21 GMT on 20 March and led to a “simultaneous loss of connection”.

The energy outage impacted 66,919 home and industrial shoppers, together with Heathrow Airport, Neso mentioned.

A big incident used to be declared via the Metropolitan Police at 00:42 and Heathrow took the verdict at 01:11 the next morning to near the airport.

Neso’s leader govt Fintan Slye mentioned: “It is important that the right lessons are learnt from this incident to prevent future instances where possible and to manage them effectively when they do occur.”

Power used to be restored to Heathrow’s substations via 06:25 the usage of circuits from any other within sight substation, Neso mentioned, and the waft of electrical energy to all 4 of Heathrow’s passenger terminals used to be restarted via 10:56.

But flights didn’t resume till after 18:00 that day. They ran throughout the evening to permit Heathrow to get again as much as complete capability.

Other shoppers’ energy used to be restored via 12:24, the file mentioned, and provide from the North Hyde substation used to be reinstated the next day.

Heathrow depends on 3 electrical energy substations, and has emergency back-up energy provides, similar to diesel turbines and batteries – however those most effective stay a very powerful protection programs working, similar to touchdown apparatus and runway lighting fixtures.

Heathrow’s leader govt Thomas Woldbye up to now mentioned the shutdown used to be brought about no longer via a loss of energy however by the point it took to change from the broken substation’s provide to the opposite operational substations.

Due to Heathrow’s “size and operational complexity”, managers determined to near the airport on protection grounds whilst this came about.

The airport mentioned on the time that its function “was to reopen as soon as safely and practically possible after the fire”.

Neso showed that the recovery of energy to the airport used to be adopted via “a period of safety checking” to make sure “safety critical systems were fully operational prior to passengers arriving at the airport”.

Heathrow mentioned in a commentary: “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.”

London Fire Brigade (LFB), which despatched 70 firefighters, mentioned on the time that the substation blaze “involved a transformer containing insulating oil which was fully alight”.

“This created a significant hazard due to being within a substation containing high-voltage equipment and the challenges of an oil-fuelled fire,” it mentioned in a commentary.

LFB defined crews needed to stay up for the transformer to chill down “before cutting through the steel casing to reach and extinguish pockets of fire that were inaccessible”.

Following the newsletter of the meantime file, Miliband mentioned: “We now await the full report to understand what happened and learn lessons to strengthen UK energy resilience and protect our critical national infrastructure.”