Heathrow Closure

Some reports have been saying that Heathrow has the demand of a fair sized city ... suddenly removing that size load from the National Grid must have been quite a challenge - presumably one that the grid controllers coped with though.

     - Andy.

Given the various shambolic official responses about “needing to reconfigure” their power, it looks like all of the 3 internal 33kV substations at Heathrow (ie. within their site) had power on the Longford leg, but had lost power on the North Hyde feed. Probably no duty HV engineer to drive round and switch the RMUs. Really appalling. 

Heathrow had enough power to avoid shutdown, says National Grid | The Independent

National Grid CEO John Pettigrew told the Financial Times: “There was no lack of capacity from the substations. Each substation individually can provide enough power to Heathrow.”

Heathrow’s management acknowledged on Friday that: "the site was served by two other substations", but claimed that, "in order for these to be used, the power supply to all terminals needed to be re-engineered."

A Heathrow spokesperson said: "It would not have been possible for Heathrow to operate uninterrupted. Hundreds of critical systems across the airport were required to be safely powered down and then safely and systematically rebooted."

It sounds like some manual reconfiguration of the in-feeds was required to reroute the supply. I find it hard to believe that automatic transfer switches were not installed for the HV distribution system. Even if manual switching was required, I'm amazed that it would have taken longer that the UPS autonomy time from critical systems.

Lots of questions. Will we ever find out the real causes?

Will we ever find out the real causes?

Well maybe, though there seems to be enough high level interest to trigger an inquiry.

It does seem pointless to have multiple in-feeds at HV if there is no  mechanism for performing the change-over faster than the hold-up time of the emergency power.
As above it sounds like the suitably qualified folk to make the technical decisions and pull the right  levers, perhaps even literally,  were not available - which is remarkable in an organization that size, even if the battle plan for such an event had to involve losing supplies to non-essential areas.

After there are plenty of other places with dual HV feeds and HV rings with zone isolation switching and so on, - consider for example that  most large hospital campuses manage this sort of thing as a matter of routine and even manage to rehearse on a semi-regular basis as well as during planned maintenance. It ought not to be that hard to have someone who understands the systems available at short notice.

Mike.

If it were up to me, I wouldn't even allow microprocessor relays without an electromechanical relay backup for the critical feeders. Putting all your trust in a microprocessor that can be programmed to burn itself up at a moments notice (or predefined future time) seems foolhardy to me - maybe I'm just paranoid.  Then again, we're constantly being told to expect cyber attacks from state actors, so why the disparity?

mapj1 said:

remarkable in an organization that size

That's usually part of the "too big to fail" problem, until the holes in the Swiss Cheese align, not forgetting that those holes can start at the edges of the cheese slices near the top layer.

It's hard to see these hairy big failures and how other systemic aspects will undermine all the planning. It's been seen in many 'big system failures'.

Some oldie but goody reading.

1. Reason, J.: ‘Human Error’ (Cambridge Univ. Pr., 1990

2. Rasmussen, J., Pejtersen, A.M., Goodstein, L.P.: ‘Cognitive systems engineering’ (J. Wiley & Sons, 1994)

True, but that's why we do Failure Modes and Effects Analyses (FMEAs) with the corresponding FMEA proving tests in other industries. No excuses for them not doing this at Heathrow.

The FMEAs are rarely done at the system of systems level (the old Conway's Law).

In this case we appear to have a supra system problem where too many sub-systems (from an airport operators viewpoint) have gone down and that has compromised all their individual backup plans, and the whole thing collapsed ('safety shutdown') from the middle (local operational safety management calling the shots) independently of any thing that some distant HV switching 'maintenance man' could do.

Interesting - any thoughts on why they would all be sat on the North Hyde feed in normal opereational mode and not distributed across the feeders e.g. 2 on North Hyde/ 1 on longford?

Although none of this answers the question as to lack of independant power back-up on the site.

Regulations vs. Reality: Where Did It Go Wrong?

The UK’s electricity distribution regulations emphasize reliability, but Heathrow’s case suggests that these safeguards might not be enough. Airports typically have multiple power feeds from different substations, ensuring automatic switching in case of failure. Heathrow, on the other hand, seems to have overlooked this critical aspect or underestimated the consequences of a single failure.

The irony? Heathrow’s terminals are designed to handle thousands of flights and passengers daily, yet a single power outage can bring this vast system to its knees.

UK regulators must mandate power redundancy for critical infrastructure to prevent similar failures in other high-risk locations.

Heathrow’s power vulnerability is a stark reminder that even the most advanced systems can crumble under a single failure point. If the busiest airport in the world can be paralyzed by something as fundamental as power supply, its A Wake-Up Call for Global Airports

In an age where cyber threats, climate-related disruptions, and grid instabilities are increasing, redundancy isn’t a luxury—it’s a necessity. Heathrow’s chaos should serve as a wake-up call for governments, regulators, and infrastructure planners worldwide: Never leave critical operations at the mercy of a single point of failure.