Heathrow Airport closed all day Friday 21 March 2025

[whole diary]

[infoman]

due to a power outage,please post the info on your many transport sites,as its gonna be chaos.

[TaplowGreen]

due to a power outage,please post the info on your many transport sites,as its gonna be chaos.

BBC^» (British Broadcasting Corporation - home page) News - https://www.bbc.co.uk/news/live/cly24zvvwxlt
Heathrow closed all day after nearby fire causes power outage - BBC News

[CyclingSid]

Is this a single point of failure?
How many other airports/airfields could be at similar risk?

Hope somebody has a spare transformer in the (very big) cupboard.

[CyclingSid]

From BBC^» (British Broadcasting Corporation - home page) Live coverage

Nearby rail services are also taking a hit
It's not just flights - trains around Heathrow are also being disrupted today.

The Heathrow Express, which connects the airport with Paddington station, says there are no services in either direction today, and is advising people not to try and travel to the airport.

On the Elizabeth Line, Transport for London says there is no service between Hayes & Harlington and Heathrow Airport, with severe delays between Paddington and Hayes & Harlington.

So far, Transport for London says that there is good service on the Piccadilly Line.

[Ralph Ayres]

Possibly not much point running an excess of trains to/from Heathrow today, as it might just encourage intending passengers to turn up and wait in vain.  Still staff needing to get there though some may have been told not to bother coming in, and it's also quite a useful coach travel hub for non-air travel, assuming the bus/coach station has enough power to operate (ditto of course the various rail stations).

[broadgage]

Is this a single point of failure?
How many other airports/airfields could be at similar risk?

Hope somebody has a spare transformer in the (very big) cupboard.

Unless a spare transformer is stored on site, or very nearby, replacement will take some time, and may require special manufacture.
I would expect power to be restored within a day or so, via an alternative route and from another transformer. This may have been achieved already.
Restarting the complex systems at Heathrow probably takes some time.
In the meantime, if an emergency requires this, aircraft could almost certainly still land.

[Electric train]

Is this a single point of failure?
How many other airports/airfields could be at similar risk?

Hope somebody has a spare transformer in the (very big) cupboard.

It certainly seems Heathrow's eggs are all in one basket.  It is poor resilience planning on the part of the Airport and the Electricity Supply Industry.

There seems to have been an internal catastrophic arc fault inside the transformer.  These transformers have a device called a Buchholz relay https://en.wikipedia.org/wiki/Buchholz_relay which trips the supply and outgoing circuit breakers in the event a surge (oil / gas) and if it detects any gassing over a period of time.  

Any arc internally will produce gasses, Hydrogen, Oxygen and Acetylene, also it has to be born in mind that an electric arc in what is in effect a sealed container produces extreme explosive pressure.  
It is normal practice for large Grid transformers to have transformer monitoring systems such as   https://camlingroup.com/kelvatek/asset-monitoring/asset-monitoring-products/transformers-monitoring and have a constant remote condition monitoring to a control centre.

What I have noticed is the lack of blast wall between the two 400/275kV / 123kV transformers (main and reserve transformers) and from the news feeds I have seen the second transformer has suffered fire damage which make a recharge of it unlikely.

I will say the "rumours" of a carelessly discarded cigarette is extremely unlikely, transformer mineral insulating oil has a very high flash point greater than 140C Grid sites have been strictly no smoking areas for many years

[TaplowGreen]

Power has been restored to Terminals 2 & 4 which were apparently the worst affected.

[CyclingSid]

I have to acknowledge that I am not a great fan of another runway at Heathrow.

"It certainly seems Heathrow's eggs are all in one basket." Adding another runway would make the situation worse; Gatwick, o
Luton or Stansted if you must.

Is all this another example of induced demand, as seen on roads? Build more and you get more, ad infinitum. Ironic that there is another closure of the M25 this weekend.

[Mark A]

Thanks for that. Ah. Blast walls. That reminded me of my unhealthy interest in taking photos of electricity-related infrastructure. Here's a photo of a transformer and associated set of blast walls on the site of Bath's vanished power station. I'm rather hoping that there's some additional structure within what is otherwise a rather tall brick wall that you'd think would be prone to being pushed over if anything gave it enough of a nudge.

Mark

[stuving]

Heathrow's supply comes from at least two grid supply points, the nearest two being North Hyde to the north (the one that went bang) and Laleham to the south. But there are others further away that could be included if resilience is the valued highly enough. SSEN^» (Scottish and Southern Electricity Networks - website) distribute power from both, but UKPN also operate at Laleham. The nominal supply area for North Hyde GSP is attached - it does not include much of the airport. But of course the big question is why the multiple supply routes to the airport did not give it a resilient supply. That's for HAL and perhaps SSEN to answer, rather than NGESO.

[Electric train]

The nominal supply area for North Hyde GSP is attached - it does not include much of the airport.

But just happens to be Term 2 & 4 along with ATC^▸ (Automatic Train Control) and other critical infrastructure 

But of course the big question is why the multiple supply routes to the airport did not give it a resilient supply. That's for HAL and perhaps SSEN^» (Scottish and Southern Electricity Networks - website) to answer, rather than NGESO.

There is either a serious design flaw, lack the right switchgear systems / control system  or lack of competent people

[stuving]

From the BBC^» (British Broadcasting Corporation - home page), in a page with further details:

With Heathrow being such a busy airport for passenger journeys and global trade, questions have been raised over whether it has back-up systems in the event of power cuts.

The BBC understands that Heathrow does have back-up power for its key systems, but kickstarting these alternative power supplies for the whole airport takes time.

A source said it was not possible to switch the power back on immediately.

A Heathrow source also told the BBC that they have "multiple sources" of energy at the airport – with diesel generators and "uninterruptable power supplies" in place.

They added when the power outage happened the back up systems "all operated as expected".

The systems, however, are not enough to run the whole airport – hence the decision to close it down.

The source said the airport is in the process of redirecting power to the affected parts of the operation – but that it "takes time".

And even once the power is back on, there are countless systems which need to be rebooted and checked to ensure they are working properly and are stable.

I would not surprised if international standards require critical systems for air operations - navigation aids, and everything that allows an aircraft to land and clear the runway at least - to be backed up independently of outside supply, and perhaps with backups for those backups. That much they are saying did work as intended.

I wonder if the fact that that was in place meant they did not worry so much about security of external supplies. So everything not critical got handled on the basis of manually reconfiguring the network - but remember that this is a big part of supply resilience at all levels (it's why restoring supply, as this morning around the dead GSP, takes several hours). And as they say, running an airport safely, even in an emergency basic no-frills mode, needs a lot more power that they (and their DNO^▸ (Distribution Network Operator)(s)) can restore via new routes within a few hours. In this case that was the result of a commercial decision made by HAL.

[stuving]

Eorostar have been running a few extra trains today - four, according to French TV news, though I could only see two when I looked online. Not much, in terms of the total number of diverted passengers, but no doubt it's good publicity to do something (and bad to do nothing). Plus, there's money to be made!

[IndustryInsider]

Plus, there's money to be made!

I saw reports that hotels were exploiting the situation by doubling, tripling and perhaps more, their standard room rates.