# The Second Heart: What Keeps an Airport Running When the Power Goes _Aviaedge analysis, based on written responses from Budapest Airport Zrt. received on 5 August 2026._ By Viktoriia Hrechukha · 2026-08-11 · Airports --- ### A Nuclear Plant Winding Down, and Every Flight on Time Hungary's electricity problem this summer began with a river. The Danube fell to record low levels, the fixed elevation cooling water pumps at the Paks nuclear plant could no longer draw what the reactors need, and output came down in stages. The scale is worth stating precisely, because it is routinely rounded off. Paks has an installed capacity of 2,000 MW and accounts for close to half of Hungarian electricity production. On 31 July it was running at 965 MW. By 3 August a single 500 MW unit remained in service at reduced load, with the plant producing 240 MW. By 5 August it was operating at just over ten percent of capacity, with a full shutdown expected and forecast to last weeks rather than days. It would be the first complete shutdown in the plant's 44 years of service. The government asked large consumers and households to reduce demand voluntarily in the evening peak between 17:00 and 22:00. They did. Reductions of 600 to 700 MW a day were reported in that window, and on one Sunday the evening peak came in at 5,700 MW against an expected 6,400 MW, a saving larger than the output of a single Paks unit. Budapest Airport announced on 31 July that it would reduce energy consumption over the following ten days, particularly between 17:00 and 22:00. The measures covered non essential building and electrical systems. Air conditioning intensity in the passenger areas of Terminal 2 was reduced during those hours. The airport said safe operation, critical infrastructure and flight handling remained uninterrupted, and asked staff and partners to save energy where possible. Flights ran. All of them. For many readers that does not follow. Close to half the country's generation is unavailable and the airport is operating normally. The explanation is that a national generation shortfall and a loss of supply at an airport are two different failures, and only one of them stops aircraft. ### Two Failures That Share a Word A generation shortfall is an economic event before it is an engineering one. There is less electricity available than the market wants. Prices rise, the system operator asks large consumers to reduce demand, and the state acquires instruments to require it if voluntary measures fall short. Hungary put such an instrument in place during this episode. Government Decree 118/2026 (VIII. 1.) entered into force at 19:00 on 1 August, amending Decree 280/2016 (IX. 21.) on measures to be taken during a major disturbance of the electricity system or an electricity supply emergency. It defines a large electricity consumer as a user with contracted capacity of at least 0.5 MW at one or more consumption sites. MAVIR may issue a voluntary request, and in more severe system states a mandatory instruction specifying a quantified consumption level. Where a mandatory instruction is not met, excess consumption may be charged at twice the relevant HUPX day ahead price, a second notice gives a two hour deadline, and if the reduction is still not made the consumer may be disconnected entirely for the duration of the emergency. An airport of Budapest's size sits well above the 0.5 MW threshold. As of early August, however, mandatory restrictions had not been imposed on large industrial consumers, because voluntary savings had been sufficient to hold the system. What a shortfall does not do, in itself, is remove electricity from a particular building. The grid holds. The airport stays connected. The cost changes and the thermostat moves. A loss of supply is a different failure. It occurs at the connection point, or within the airport's own distribution, and it is unrelated to the national generation balance. European and North American precedents from the past decade, including substation and tunnel fires and one peninsula wide outage, fall into this second category rather than the first. Same word. Different failure. ### What Budapest Told Us Aviaedge put four questions to Budapest Airport Zrt. on 2 August. The airport responded in writing on 5 August. On redundancy at the point of grid connection, the airport said that redundancy exists. That was the extent of the question. Configuration is operationally sensitive, it was not requested, and it is not published here. On the national restriction order, the airport did not state whether it considers itself to be in a category exempt from mandatory curtailment. It said that like all other significant industrial consumers it had made every effort to implement exceptional energy efficiency measures during critical periods to help relieve electrical loads across the country, regardless of its interpretation of applicable legislation, and referred to its published information on reducing energy consumption. The classification of consumers under the national framework is a matter for the transmission system operator and the responsible authorities rather than for the airport. The remaining two answers extend beyond Hungary. ### The Solar Park and the Island Mode Question Asked whether its 7.5 MWp solar park is in operation, and if so whether it could supply the airport in island mode during a grid outage, Budapest Airport said it is not yet in operation. The answer closes a question that has been open in the public record, and it also addresses a common assumption. On site solar without islanding capability disconnects when the grid does, because the inverter shuts down with it. Panels on a roof do not, in themselves, keep an airport running during an outage. A solar park is a decarbonisation asset and an energy cost asset. Whether it is also a resilience asset depends on whether islanding capability has been designed in. The project has a documented history. A 7.5 MW park was described as in planning in September 2022, with construction expected to begin the following year, and as in planning again in December 2023. In April 2024, Airport Carbon Accreditation materials recorded ongoing work to develop a 7.5 MW solar farm alongside preparation of a geothermal heating system. The airport's own 2024 sustainability report, published in December 2025, gave the figure as 7.2 MWp and stated that construction could start that year. In February 2026, at the groundbreaking for the Terminal+ development, a 7.2 MW array was described as planned for the roof of the new central terminal building. No public source has stated that the park is generating, and the airport has now confirmed that it is not. ### The Apron That Used to Run on Diesel ICAO Annex 14, Volume I, Table 8-1, in the seventh edition of July 2016, sets out which visual aids must be supported by secondary power supply and how quickly the changeover must occur. The requirement is more granular than it is usually described. For a Category I precision approach runway the maximum switch over time is fifteen seconds across the listed aids. For Category II and III operations, one second applies to the inner 300 metres of the approach lighting system, the runway threshold, the runway end, the runway centre line, the touchdown zone and all stop bars, while the runway edge, the remaining parts of the approach lighting system and essential taxiways remain at fifteen seconds. The European equivalent is CS ADR-DSN.S.880 and Table S-1 in the EASA Certification Specifications for Aerodrome Design, with CS ADR-DSN.S.875 covering electrical supply to air navigation facilities. Approach and runway lighting. Air traffic control and navigation aids. The systems an aircraft needs in order to arrive. Baggage handling, hold baggage screening, boarding bridges, security lanes, fuel hydrant pumps and departure control systems are not part of that requirement, and there was a reason for it. None of them is a landing aid, and at the time the provisions were drafted the apron did not depend on electricity to move an aircraft. It ran on diesel. That has changed. Budapest Airport reported in January 2023 that 134 ground handling vehicles and 24 fleet and management vehicles had been replaced, saving 412,000 litres of fuel. By April 2024 the airport had 96 charging points available and more than 130 units of electric ground service equipment in daily operation, with a further 35 charging points in public car parks for passengers. A grant contract covers 83 charging stations and 102 charging points, supported by close to 650 million forint from the EU CEF 2 Alternative Fuels Infrastructure Facility. The airport also reports that since January 2023 its total electricity consumption has been covered by renewable energy sources, which is a matter of supply contracting and does not alter what happens during an outage. Those figures belong in the emissions column, where the airport reports them. The point here is separate. Equipment that previously operated without the grid now depends on it, while the regulatory list of systems that must be maintained without the grid has not changed. ### The Second Heart Asked whether the scope of systems covered by secondary power supply has been reviewed since the electrification of ground support equipment, Budapest Airport said yes, and that not only the electrification of ground support equipment but also the growth of the airport and the foreseen developments make the review necessary. Aviaedge asked the airport to confirm whether that review is currently under way or is anticipated as part of the developments referred to. No further response had been received at the time of publication, and the answer is therefore reported as given. What the answer establishes is that an operator with one of the more advanced apron electrification programmes in Europe considers a review of secondary power supply scope to be necessary, and attributes that necessity to three factors rather than one. This is not specific to Budapest. European airports are electrifying their aprons under the same funding instruments and the same decarbonisation targets, against provisions drafted for an apron that did not depend on electricity to move an aircraft. The secondary supply still does what it was designed to do. The lights come on, the navigation aids hold, air traffic control continues, and an aircraft can find the runway and land. What is available on the ground afterwards is a separate matter. The equipment that tows it, loads it, screens its bags and fuels it sits outside the requirement, as does the infrastructure that charges that equipment. The aircraft can land. It can be seen, guided and brought down safely. Whether it can depart again is a question the provisions do not currently address. Aviaedge is an independent non profit aviation publication covering European and Ukrainian aviation, published in English, Ukrainian and German at aviaedge.com. Budapest Airport Zrt. responded in writing to four questions on 5 August 2026. This piece is not sponsored. Aviaedge thanks the Budapest Airport communication team for its response. --- Source: https://aviaedge.com/en/airports/the-second-heart-what-keeps-an-airport-running