Heathrow Airport Power Outage 2025 disrupted operations with mass flight cancellations and diversions after a grid failure, exposing infrastructure resilience gaps, crisis management flaws, and raising passenger compensation and safety oversight concerns.
Key Points
A grid failure closed Heathrow, causing mass cancellations and diversions, exposing resilience and communication lapses.
On March 21, 2025, Heathrow Airport, Europe's busiest, suffered a catastrophic power outage, similar to another high-profile outage seen at major events, that led to the cancellation and diversion of over 1,400 flights, affecting nearly 300,000 passengers and costing airlines an estimated £100 million. The power failure, triggered by a fire at an electricity substation in west London, left Heathrow with a significant operational crisis. This disruption is even more significant considering that Heathrow is one of the most expensive airports globally, which raises concerns about its infrastructure resilience and broader electricity system resilience across Europe.
In a parliamentary committee meeting, Heathrow officials admitted that vulnerabilities in the airport’s power supply were flagged just days before the outage. Nigel Wicking, Chief Executive of the Heathrow Airline Operators' Committee (HAOC), informed MPs that concerns regarding power resilience had been raised on March 15, following disruptions caused by cable thefts impacting runway lights. Despite these warnings, the airport’s management did not address the vulnerabilities urgently, even as UK net zero policies continue to reshape infrastructure planning, which ultimately led to the disastrous outage.
The airport was closed for a day, with serious consequences for not only airlines but also the surrounding community and businesses. British Airways alone faced millions of pounds in losses, and passengers experienced significant emotional distress, missing vital life events like weddings and funerals due to flight cancellations. The committee is now questioning officials from National Grid and Scottish and Southern Electricity Networks to better understand why Heathrow’s infrastructure failed, in the context of a cleaner grid following the British carbon tax that reduced coal use, how it communicated with affected parties, and what measures will be taken to compensate impacted passengers.
Heathrow’s Chief Executive, Thomas Woldbye, defended the closure decision, stating it would have been disastrous to keep the airport open under such circumstances. He noted that continuing operations would have left tens of thousands of passengers stranded and would have posed safety risks due to the failure of fire surveillance and CCTV systems. However, Wicking, representing the airlines, pointed out that Heathrow’s lack of resilience was unacceptable given the amount spent on the airport, emphasizing the need for better infrastructure, including addressing SF6 in switchgear during upgrades, and more transparent management practices.
Looking forward, the MPs intend to investigate the airport’s emergency preparedness, why the resilience review from 2018 wasn’t shared with airlines, and whether enough preventative measures were in place amid surging data demand that could strain electricity supplies. The outcome of this inquiry could have lasting effects on how Heathrow and other major airports handle their infrastructure and crisis management systems, as drought-driven hydro challenges demonstrate the wider climate stresses on power networks.
Puerto Rico Power Restoration advances as PREPA, FEMA, and the Army Corps rebuild the grid after Hurricane Maria; 75% of customers powered, amid privatization debate, Whitefish contract fallout, and a continuing island-wide boil-water advisory.
Key Points
Effort to rebuild Puerto Rico's grid and restore power, led by PREPA with FEMA support after Hurricane Maria.
✅ 75.35% of customers have power; 90.8% grid generating
✅ PREPA, FEMA, and Army Corps lead restoration work
Nearly six months after Hurricane Maria decimated Puerto Rico, the island's electricity has been restored to 75 percent capacity, according to its utility company, a contrast to California power shutdowns implemented for different reasons.
The Puerto Rico Electric Power Authority said Sunday that 75.35 percent of customers now have electricity. It added that 90.8 percent of the electrical grid, already anemic even before the Sept. 20 storm barrelled through the island, is generating power again, though demand dynamics can vary widely as seen in Spain's power demand during lockdowns.
Thousands of power restoration personnel made up of the Puerto Rico Electric Power Authority (PREPA), the Federal Emergency Management Agency (FEMA), industry workers from the mainland, and the Army Corps of Engineers have made marked progress in recent weeks, even as California power shutoffs highlight grid risks elsewhere.
Despite this, 65 people in shelters and an island-wide boil water advisory is still in effect even though almost 100 percent of Puerto Ricans have access to drinking water, local government records show.
The issue of power became controversial after Puerto Rico Gov. Ricardo Rossello recently announced plans to privatize PREPA after it chose to allocate a $300 million power restoration contract to Whitefish, a Montana-based company with only a few staffers, rather than put it through the mutual-aid network of public utilities usually called upon to coordinate power restoration after major disasters, and unlike investor-owned utilities overseen by regulators such as the Florida PSC on the mainland.
That contract was nixed and Whitefish stopped working in Puerto Rico after FEMA raised "significant concerns" over the procurement process, scrutiny mirrored by the fallout from Taiwan's widespread outage where the economic minister resigned.
Columbia River Treaty Negotiations involve Canada-U.S. talks on B.C. dams, flood control, hydropower sharing, and downstream benefits, prioritizing ecosystem health, First Nations rights, and salmon restoration while balancing affordable electricity for northwest consumers.
Key Points
Talks to update flood control, hydropower, and ecosystem terms for fair benefits to B.C. and U.S. communities.
✅ Public consultations across B.C.'s Columbia Basin
✅ First Nations priorities include salmon restoration
✅ U.S. seeks cheaper power; B.C. defends downstream benefits
With talks underway between Canada and the U.S. on the future of the Columbia River Treaty, the B.C. New Democrats have launched public consultations in the region most affected by the high-stakes negotiation.
“We want to ensure Columbia basin communities are consulted, kept informed and have their voices heard,” said provincial cabinet minister Katrine Conroy via a press release announcing meetings this month in Castlegar, Golden, Revelstoke, Nakusp, Nelson and other communities.
As well as having cabinet responsibility for the talks, Conroy’s Kootenay West riding includes several places that were inundated under the terms of the 1964 flood control and power generation treaty.
“We will continue to work closely with First Nations affected by the treaty, to ensure Indigenous interests are reflected in the negotiations,” she added by way of consolation to Indigenous people who’ve been excluded from the negotiating teams on both sides of the border.
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The stakes are also significant for the province as a whole. The basics of the treaty saw B.C. build dams to store water on this side of the border, easing the flood risk in the U.S. and allowing the flow to be evened out through the year. In exchange, B.C. was entitled to a share of the additional hydro power that could be generated in dams on the U.S. side.
B.C.’s sale of those downstream benefits to the U.S has poured almost $1.4 billion into provincial coffers over the past 10 years, albeit at a declining rate these days amid scrutiny from a regulator report on BC Hydro that raised concerns, because of depressed prices for cross-border electricity sales.
Politicians on the U.S. side have long sought to reopen the treaty, believing there was now a case for reducing B.C.’s entitlement.
They did not get across the threshold under President Barack Obama.
Then, last fall his successor Donald Trump served notice of intent, initiating the formal negotiations that commenced with a two day session last week in Washington, D.C. The next round is set for mid-August in B.C.
American objectives in the talks include “continued, careful management of flood risk; ensuring a reliable and economical power supply; and better addressing ecosystem concerns,” with recognition of recent BC Hydro demand declines during the pandemic.
“Economical power supply,” being a diplomatic euphemism for “cheaper electricity for consumers in the northwest states,” achievable by clawing back most of B.C.’s treaty entitlement.
On taking office last summer, the NDP inherited a 14-point statement of principles setting out B.C. hopes for negotiations to “continue the treaty” while “seeking improvements within the existing framework” of the 54-year-old agreement.
The New Democrats have endorsed those principles in a spirit of bipartisanship, even as Manitoba Hydro governance disputes play out elsewhere in Canada.
“Those principles were developed with consultation from throughout the region,” as Conroy advised the legislature this spring. “So I was involved, as well, in the process and knew what the issues were, right as they would come up.”
The New Democrats did chose to put additional emphasis on some concerns.
“There is an increase in discussion with Canada and First Nations on the return of salmon to the river,” she advised the house, recalling how construction of the enormous Grand Coulee Dam on the U.S. side in the 1930s wiped out salmon runs on the upper Columbia River.
“There was no consideration then for how incredibly important salmon was, especially to the First Nations people in our region. We have an advisory table that is made up of Indigenous representation from our region, and also we are discussing with Canada that we need to see if there’s feasibility here.”
As to feasibility, the obstacles to salmon migration in the upper reaches of the Columbia include the 168-metre high Grand Coulee and the 72-metre Chief Joseph dams on the U.S. side, plus the Keenleyside (52 metres), Revelstoke (175 metres) and Mica (240 metres) dams on the Canadian side.
Still, says Conroy “the First Nations from Canada and the tribes from the United States, have been working on scientific and technical documents and research to see if, first of all, the salmon can come up, how they can come up, and what the things are that have to be done to ensure that happens.”
The New Democrats also put more emphasis on preserving the ecosystem, aligning with clean-energy efforts with First Nations that support regional sustainability.
“I know that certainly didn’t happen in 1964, but that is something that’s very much on the minds of people in the Columbia basin,” said Conroy. “If we are going to tweak the treaty, what can we do to make sure the voices of the basin are heard and that things that were under no consideration in the ’60s are now a topic for consideration?”
With those new considerations, there’s still the status quo concern of preserving the downstream benefits as a trade off for the flooding and other impacts on this side of the border.
The B.C. position on that score is the same under the New Democrats as it was under the Liberals, despite a B.C. auditor general report on deferred BC Hydro costs.
“The level of benefits to B.C., which is currently solely in the form of the (electricity) entitlement, does not account for the full range of benefits in the U.S. or the impacts in B.C.,” says the statement of principle.
“All downstream U.S. benefits such as flood risk management, hydropower, ecosystems, water supply (including municipal, industrial and agricultural uses), recreation, navigation and other related benefits should be accounted for and such value created should be shared equitably between the two countries.”
No surprise if the Americans do not see it the same way. But that is a topic for another day.
EU Winter Energy Mix 2022-2023 shows renewables, wind, solar, and hydro overtaking coal and gas, as demand fell amid high prices; Ember and IEA confirm lower emissions across Europe during the energy crisis.
Key Points
It describes Europe's winter power mix: reduced coal and gas, and record wind, solar, and hydro output.
✅ Coal generation fell 11% YoY; gas output declined even more.
✅ Ember and IEA confirm trends; mild winter tempered demand.
The EU burned less coal this winter during the energy crisis than in previous years, according to an analysis, quashing fears that consumption of the most polluting fossil fuel would soar as countries scrambled to find substitutes for lost supplies of Russian gas.
The study from energy think-tank Ember shows that between October 2022 and March 2023 coal generation fell 27 terawatt hours, or almost 11 per cent year on year, while gas generation fell 38 terawatt hours, as renewables crowded out gas and consumers cut electricity consumption in response to soaring prices.
Renewable energy supplies also rose, with combined wind and solar power and hydroelectric output outstripping fossil fuel generation for the first time, providing 40 per cent of all electricity supplies. The Financial Times checked Ember’s findings with the International Energy Agency, which said they broadly matched its own preliminary analysis of Europe’s electricity generation over the winter.
The study demonstrates that fears of a steep rebound in coal usage in Europe’s power mix were overstated, despite the continent’s worst energy crisis in 40 years following Russia’s full-scale invasion of Ukraine, even as stunted hydro and nuclear output in parts of Europe posed challenges.
While Russia slashed gas supplies to Europe and succeeded in boosting energy prices for consumers to record levels, the push by governments to rejuvenate old coal plants, including Germany's coal generation, to ensure the lights stayed on ultimately did not lead to increased consumption.
“With Europe successfully on the other side of this winter and major supply disruptions avoided, it is clear the threatened coal comeback did not materialise,” analysts at Ember said in the report.
“With fossil fuel generation down, EU power sector emissions during winter were the lowest they have ever been.”
Ember cautioned, however, that Europe had been assisted by a mild winter that helped cut electricity demand for heating and there was no guarantee of such weather next winter. Companies and households had also endured a lot of pain as a result of the higher prices that had led them to cut consumption, even though in some periods, such as the latest lockdown, power demand held firm in parts of Europe.
Total electricity consumption between October and March declined 94 terawatt hours, or 7 per cent, compared with the same period in winter 2021/22, continuing post-Covid transition dynamics across Europe.
“For a lot of people this winter was really hard with electricity prices that were extraordinarily high and we shouldn’t lose sight of that,” said Ember analyst Harriet Fox.
Ontario Global Adjustment Deferral provides COVID-19 relief to industrial and commercial electricity consumers, holding GA charges at pre-COVID levels, aligning Class A and Class B rates, and deferring non-RPP costs from April to June 2020.
Key Points
An emergency measure that defers a portion of GA charges to stabilize electricity bills for non-RPP Class A/B consumers.
✅ Holds GA near pre-COVID levels at $115/MWh for Class B.
✅ Applies equal percentage relief to Class A customers.
✅ Deferred costs recovered over 12 months from Jan 2021.
Through an emergency order passed today, the Ontario government is taking steps to defer a portion of Global Adjustment (GA) charges for industrial and commercial electricity consumers that do not participate in the Regulated Price Plan for the period starting from April 2020, at a time when Toronto's growing electricity needs require careful planning. This initiative is intended to provide companies with temporary immediate relief on their monthly electricity bills, as utilities use AI to adapt to shifting electricity demands in April, May and June 2020. The government intends to keep this emergency order in place until May 31, 2020, and subsequent regulatory amendments would, if approved, provide for the deferral of these charges for June 2020 as well.
This relief will prevent a marked increase in Global Adjustment charges due to the low electricity demand caused by the COVID-19 outbreak. Without this emergency order, a small industrial or commercial consumer (i.e., Class B) could have seen bills increase by 15 per cent or more. This emergency order will hold GA rates in line with pre-COVID-19 levels, even as clean energy initiatives in British Columbia accelerate across the sector.
"Ontario's industrial and commercial electricity consumers are being impacted by COVID-19. They employ thousands of hardworking Ontarians, and we know this is a challenging time for them," said Greg Rickford, Minister of Energy, Northern Development and Mines. "This would provide immediate financial support for more than 50,000 companies when they need it most: as they do their part to stop the spread of COVID-19 and as they prepare to help get our economy moving again with Toronto preparing for a surge in electricity demand in the years ahead."
Quick Facts
The GA rate for smaller industrial and commercial consumers (i.e., Class B) has been set at $115 per megawatt-hour, which is roughly in line with the March 2020 value, alongside efforts to develop IoT security standards for electricity sector devices today. Large industrial and commercial consumers (i.e., Class A) will receive the same percentage reduction in GA charges as Class B consumers.
Subject to the approval of subsequent amendments, deferred costs would be recovered over a 12-month period beginning in January 2021, amid increasing exposure to harsh weather across Canadian grids.
Infrastructure Security Algorithm prioritizes cyber defense for power grids and critical infrastructure, mitigating ransomware, blackout risks, and cascading failures by guiding utilities, regulators, and cyber insurers on optimal security investment allocation.
Key Points
An algorithm that optimizes security spending to cut ransomware and blackout risks across critical infrastructure.
✅ Guides utilities on optimal security allocation
✅ Uses incentives to correct human risk biases
✅ Prioritizes assets to prevent cascading outages
Millions of people could suddenly lose electricity if a ransomware attack just slightly tweaked energy flow onto the U.S. power grid, as past US utility intrusions have shown.
No single power utility company has enough resources to protect the entire grid, but maybe all 3,000 of the grid's utilities could fill in the most crucial security gaps if there were a map showing where to prioritize their security investments.
Purdue University researchers have developed an algorithm to create that map. Using this tool, regulatory authorities or cyber insurance companies could establish a framework for protecting the U.S. power grid that guides the security investments of power utility companies to parts of the grid at greatest risk of causing a blackout if hacked.
Power grids are a type of critical infrastructure, which is any network - whether physical like water systems or virtual like health care record keeping - considered essential to a country's function and safety. The biggest ransomware attacks in history have happened in the past year, affecting most sectors of critical infrastructure in the U.S. such as grain distribution systems in the food and agriculture sector and the Colonial Pipeline, which carries fuel throughout the East Coast, prompting increased military preparation for grid hacks in the U.S.
With this trend in mind, Purdue researchers evaluated the algorithm in the context of various types of critical infrastructure in addition to the power sector, including electricity-sector IoT devices that interface with grid operations. The goal is that the algorithm would help secure any large and complex infrastructure system against cyberattacks.
"Multiple companies own different parts of infrastructure. When ransomware hits, it affects lots of different pieces of technology owned by different providers, so that's what makes ransomware a problem at the state, national and even global level," said Saurabh Bagchi, a professor in the Elmore Family School of Electrical and Computer Engineering and Center for Education and Research in Information Assurance and Security at Purdue. "When you are investing security money on large-scale infrastructures, bad investment decisions can mean your power grid goes out, or your telecommunications network goes out for a few days."
Protecting infrastructure from hacks by improving security investment decisions
The researchers tested the algorithm in simulations of previously reported hacks to four infrastructure systems: a smart grid, industrial control system, e-commerce platform and web-based telecommunications network. They found that use of this algorithm results in the most optimal allocation of security investments for reducing the impact of a cyberattack.
The team's findings appear in a paper presented at this year's IEEE Symposium on Security and Privacy, the premier conference in the area of computer security. The team comprises Purdue professors Shreyas Sundaram and Timothy Cason and former PhD students Mustafa Abdallah and Daniel Woods.
"No one has an infinite security budget. You must decide how much to invest in each of your assets so that you gain a bump in the security of the overall system," Bagchi said.
The power grid, for example, is so interconnected that the security decisions of one power utility company can greatly impact the operations of other electrical plants. If the computers controlling one area's generators don't have adequate security protection, as seen when Russian hackers accessed control rooms at U.S. utilities, then a hack to those computers would disrupt energy flow to another area's generators, forcing them to shut down.
Since not all of the grid's utilities have the same security budget, it can be hard to ensure that critical points of entry to the grid's controls get the most investment in security protection.
The algorithm that Purdue researchers developed would incentivize each security decision maker to allocate security investments in a way that limits the cumulative damage a ransomware attack could cause. An attack on a single generator, for instance, would have less impact than an attack on the controls for a network of generators, which sophisticated grid-disruption malware can target at scale, rather than for the protection of a single generator.
Building an algorithm that considers the effects of human behavior
Bagchi's research shows how to increase cybersecurity in ways that address the interconnected nature of critical infrastructure but don't require an overhaul of the entire infrastructure system to be implemented.
As director of Purdue's Center for Resilient Infrastructures, Systems, and Processes, Bagchi has worked with the U.S. Department of Defense, Northrop Grumman Corp., Intel Corp., Adobe Inc., Google LLC and IBM Corp. on adopting solutions from his research. Bagchi's work has revealed the advantages of establishing an automatic response to attacks, and analyses like Symantec's Dragonfly report highlight energy-sector risks, leading to key innovations against ransomware threats, such as more effective ways to make decisions about backing up data.
There's a compelling reason why incentivizing good security decisions would work, Bagchi said. He and his team designed the algorithm based on findings from the field of behavioral economics, which studies how people make decisions with money.
"Before our work, not much computer security research had been done on how behaviors and biases affect the best defense mechanisms in a system. That's partly because humans are terrible at evaluating risk and an algorithm doesn't have any human biases," Bagchi said. "But for any system of reasonable complexity, decisions about security investments are almost always made with humans in the loop. For our algorithm, we explicitly consider the fact that different participants in an infrastructure system have different biases."
To develop the algorithm, Bagchi's team started by playing a game. They ran a series of experiments analyzing how groups of students chose to protect fake assets with fake investments. As in past studies in behavioral economics, they found that most study participants guessed poorly which assets were the most valuable and should be protected from security attacks. Most study participants also tended to spread out their investments instead of allocating them to one asset even when they were told which asset is the most vulnerable to an attack.
Using these findings, the researchers designed an algorithm that could work two ways: Either security decision makers pay a tax or fine when they make decisions that are less than optimal for the overall security of the system, or security decision makers receive a payment for investing in the most optimal manner.
"Right now, fines are levied as a reactive measure if there is a security incident. Fines or taxes don't have any relationship to the security investments or data of the different operators in critical infrastructure," Bagchi said.
In the researchers' simulations of real-world infrastructure systems, the algorithm successfully minimized the likelihood of losing assets to an attack that would decrease the overall security of the infrastructure system.
Bagchi's research group is working to make the algorithm more scalable and able to adapt to an attacker who may make multiple attempts to hack into a system. The researchers' work on the algorithm is funded by the National Science Foundation, the Wabash Heartland Innovation Network and the Army Research Lab.
Cybersecurity is an area of focus through Purdue's Next Moves, a set of initiatives that works to address some of the greatest technology challenges facing the U.S. Purdue's cybersecurity experts offer insights and assistance to improve the protection of power plants, electrical grids and other critical infrastructure.
Boeing 787 More-Electric Architecture replaces pneumatics with bleedless pressurization, VFSG starter-generators, electric brakes, and heated wing anti-ice, leveraging APU, RAT, batteries, and airport ground power for efficient, redundant electrical power distribution.
Key Points
An integrated, bleedless electrical system powering start, pressurization, brakes, and anti-ice via VFSGs, APU and RAT.
✅ VFSGs start engines, then generate 235Vac variable-frequency power
✅ Bleedless pressurization, electric anti-ice improve fuel efficiency
✅ Electric brakes cut hydraulic weight and simplify maintenance
The 787 Dreamliner is different to most commercial aircraft flying the skies today. On the surface it may seem pretty similar to the likes of the 777 and A350, but get under the skin and it’s a whole different aircraft.
When Boeing designed the 787, in order to make it as fuel efficient as possible, it had to completely shake up the way some of the normal aircraft systems operated. Traditionally, systems such as the pressurization, engine start and wing anti-ice were powered by pneumatics. The wheel brakes were powered by the hydraulics. These essential systems required a lot of physical architecture and with that comes weight and maintenance. This got engineers thinking.
What if the brakes didn’t need the hydraulics? What if the engines could be started without the pneumatic system? What if the pressurisation system didn’t need bleed air from the engines? Imagine if all these systems could be powered electrically… so that’s what they did.
Power sources
The 787 uses a lot of electricity. Therefore, to keep up with the demand, it has a number of sources of power, much as grid operators track supply on the GB energy dashboard to balance loads. Depending on whether the aircraft is on the ground with its engines off or in the air with both engines running, different combinations of the power sources are used.
Engine starter/generators
The main source of power comes from four 235Vac variable frequency engine starter/generators (VFSGs). There are two of these in each engine. These function as electrically powered starter motors for the engine start, and once the engine is running, then act as engine driven generators.
The generators in the left engine are designated as L1 and L2, the two in the right engine are R1 and R2. They are connected to their respective engine gearbox to generate electrical power directly proportional to the engine speed. With the engines running, the generators provide electrical power to all the aircraft systems.
APU starter/generators
In the tail of most commercial aircraft sits a small engine, the Auxiliary Power Unit (APU). While this does not provide any power for aircraft propulsion, it does provide electrics for when the engines are not running.
The APU of the 787 has the same generators as each of the engines — two 235Vac VFSGs, designated L and R. They act as starter motors to get the APU going and once running, then act as generators. The power generated is once again directly proportional to the APU speed.
The APU not only provides power to the aircraft on the ground when the engines are switched off, but it can also provide power in flight should there be a problem with one of the engine generators.
Battery power
The aircraft has one main battery and one APU battery. The latter is quite basic, providing power to start the APU and for some of the external aircraft lighting.
The main battery is there to power the aircraft up when everything has been switched off and also in cases of extreme electrical failure in flight, and in the grid context, alternatives such as gravity power storage are being explored for long-duration resilience. It provides power to start the APU, acts as a back-up for the brakes and also feeds the captain’s flight instruments until the Ram Air Turbine deploys.
Ram air turbine (RAT) generator
When you need this, you’re really not having a great day. The RAT is a small propeller which automatically drops out of the underside of the aircraft in the event of a double engine failure (or when all three hydraulics system pressures are low). It can also be deployed manually by pressing a switch in the flight deck.
Once deployed into the airflow, the RAT spins up and turns the RAT generator. This provides enough electrical power to operate the captain’s flight instruments and other essentials items for communication, navigation and flight controls.
External power
Using the APU on the ground for electrics is fine, but they do tend to be quite noisy. Not great for airports wishing to keep their noise footprint down. To enable aircraft to be powered without the APU, most big airports will have a ground power system drawing from national grids, including output from facilities such as Barakah Unit 1 as part of the mix. Large cables from the airport power supply connect 115Vac to the aircraft and allow pilots to shut down the APU. This not only keeps the noise down but also saves on the fuel which the APU would use.
The 787 has three external power inputs — two at the front and one at the rear. The forward system is used to power systems required for ground operations such as lighting, cargo door operation and some cabin systems. If only one forward power source is connected, only very limited functions will be available.
The aft external power is only used when the ground power is required for engine start.
Circuit breakers
Most flight decks you visit will have the back wall covered in circuit breakers — CBs. If there is a problem with a system, the circuit breaker may “pop” to preserve the aircraft electrical system. If a particular system is not working, part of the engineers procedure may require them to pull and “collar” a CB — placing a small ring around the CB to stop it from being pushed back in. However, on the 787 there are no physical circuit breakers. You’ve guessed it, they’re electric.
Within the Multi Function Display screen is the Circuit Breaker Indication and Control (CBIC). From here, engineers and pilots are able to access all the “CBs” which would normally be on the back wall of the flight deck. If an operational procedure requires it, engineers are able to electrically pull and collar a CB giving the same result as a conventional CB.
Not only does this mean that the there are no physical CBs which may need replacing, it also creates space behind the flight deck which can be utilised for the galley area and cabin.
A normal flight
While it’s useful to have all these systems, they are never all used at the same time, and, as the power sector’s COVID-19 mitigation strategies showed, resilience planning matters across operations. Depending on the stage of the flight, different power sources will be used, sometimes in conjunction with others, to supply the required power.
On the ground
When we arrive at the aircraft, more often than not the aircraft is plugged into the external power with the APU off. Electricity is the blood of the 787 and it doesn’t like to be without a good supply constantly pumping through its system, and, as seen in NYC electric rhythms during COVID-19, demand patterns can shift quickly. Ground staff will connect two forward external power sources, as this enables us to operate the maximum number of systems as we prepare the aircraft for departure.
Whilst connected to the external source, there is not enough power to run the air conditioning system. As a result, whilst the APU is off, air conditioning is provided by Preconditioned Air (PCA) units on the ground. These connect to the aircraft by a pipe and pump cool air into the cabin to keep the temperature at a comfortable level.
APU start
As we near departure time, we need to start making some changes to the configuration of the electrical system. Before we can push back , the external power needs to be disconnected — the airports don’t take too kindly to us taking their cables with us — and since that supply ultimately comes from the grid, projects like the Bruce Power upgrade increase available capacity during peaks, but we need to generate our own power before we start the engines so to do this, we use the APU.
The APU, like any engine, takes a little time to start up, around 90 seconds or so. If you remember from before, the external power only supplies 115Vac whereas the two VFSGs in the APU each provide 235Vac. As a result, as soon as the APU is running, it automatically takes over the running of the electrical systems. The ground staff are then clear to disconnect the ground power.
If you read my article on how the 787 is pressurised, you’ll know that it’s powered by the electrical system. As soon as the APU is supplying the electricity, there is enough power to run the aircraft air conditioning. The PCA can then be removed.
Engine start
Once all doors and hatches are closed, external cables and pipes have been removed and the APU is running, we’re ready to push back from the gate and start our engines. Both engines are normally started at the same time, unless the outside air temperature is below 5°C.
On other aircraft types, the engines require high pressure air from the APU to turn the starter in the engine. This requires a lot of power from the APU and is also quite noisy. On the 787, the engine start is entirely electrical.
Power is drawn from the APU and feeds the VFSGs in the engines. If you remember from earlier, these fist act as starter motors. The starter motor starts the turn the turbines in the middle of the engine. These in turn start to turn the forward stages of the engine. Once there is enough airflow through the engine, and the fuel is igniting, there is enough energy to continue running itself.
After start
Once the engine is running, the VFSGs stop acting as starter motors and revert to acting as generators. As these generators are the preferred power source, they automatically take over the running of the electrical systems from the APU, which can then be switched off. The aircraft is now in the desired configuration for flight, with the 4 VFSGs in both engines providing all the power the aircraft needs.
As the aircraft moves away towards the runway, another electrically powered system is used — the brakes. On other aircraft types, the brakes are powered by the hydraulics system. This requires extra pipe work and the associated weight that goes with that. Hydraulically powered brake units can also be time consuming to replace.
By having electric brakes, the 787 is able to reduce the weight of the hydraulics system and it also makes it easier to change brake units. “Plug in and play” brakes are far quicker to change, keeping maintenance costs down and reducing flight delays.
In-flight
Another system which is powered electrically on the 787 is the anti-ice system. As aircraft fly though clouds in cold temperatures, ice can build up along the leading edge of the wing. As this reduces the efficiency of the the wing, we need to get rid of this.
Other aircraft types use hot air from the engines to melt it. On the 787, we have electrically powered pads along the leading edge which heat up to melt the ice.
Not only does this keep more power in the engines, but it also reduces the drag created as the hot air leaves the structure of the wing. A double win for fuel savings.
Once on the ground at the destination, it’s time to start thinking about the electrical configuration again. As we make our way to the gate, we start the APU in preparation for the engine shut down. However, because the engine generators have a high priority than the APU generators, the APU does not automatically take over. Instead, an indication on the EICAS shows APU RUNNING, to inform us that the APU is ready to take the electrical load.
Shutdown
With the park brake set, it’s time to shut the engines down. A final check that the APU is indeed running is made before moving the engine control switches to shut off. Plunging the cabin into darkness isn’t a smooth move. As the engines are shut down, the APU automatically takes over the power supply for the aircraft. Once the ground staff have connected the external power, we then have the option to also shut down the APU.
However, before doing this, we consider the cabin environment. If there is no PCA available and it’s hot outside, without the APU the cabin temperature will rise pretty quickly. In situations like this we’ll wait until all the passengers are off the aircraft until we shut down the APU.
Once on external power, the full flight cycle is complete. The aircraft can now be cleaned and catered, ready for the next crew to take over.
Bottom line
Electricity is a fundamental part of operating the 787. Even when there are no passengers on board, some power is required to keep the systems running, ready for the arrival of the next crew. As we prepare the aircraft for departure and start the engines, various methods of powering the aircraft are used.
The aircraft has six electrical generators, of which only four are used in normal flights. Should one fail, there are back-ups available. Should these back-ups fail, there are back-ups for the back-ups in the form of the battery. Should this back-up fail, there is yet another layer of contingency in the form of the RAT. A highly unlikely event.
The 787 was built around improving efficiency and lowering carbon emissions whilst ensuring unrivalled levels safety, and, in the wider energy landscape, perspectives like nuclear beyond electricity highlight complementary paths to decarbonization — a mission it’s able to achieve on hundreds of flights every single day.
