Nearly 300,000 passengers will experience flight disruption to and from Heathrow, with the airport closed for the whole day following a massive fire at a nearby electrical substation.

A transformer within the North Hyde electrical substation caught fire in west London on Thursday night, leaving thousands of homes without power.

Aviation analytics firm Cirium said the airport was scheduled to have 665 departures today, equating to over 145,094 seats. A further 669 flights were due to arrive today, with some 145,000 passengers expected to land in the UK’s busiest airport.

Heathrow was due to see more than 1,330 scheduled flights on Friday, flying some 291,000 passengers, Cirium said.

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British Airways had the largest share of flights from the airport (51 per cent), followed by Virgin Atlantic and Lufthansa, the aviation analytics firm found.

Online flight tracking service FlightRadar24 said 120 flights to the airport were in the air when the closure was announced.

Online tracking services showed flights were diverted to Gatwick, Charles de Gaulle Airport in Paris and Ireland’s Shannon Airport.

Several flights were also turned around and returned to airports in Canada and the United States.

Gatwick Airport confirmed it had accepted seven diverted flights from Singapore, Johannesburg, Lagos, Cape Town and Doha which were originally destined for Heathrow.

Virgin Atlantic passengers from Barbados had their flight diverted to Cardiff Airport.

Shannon Airport in Co Clare confirmed it had accepted six diverted flights from Toronto, Atlanta, Bridgetown Barbados, Boston, Orlando and Newark.

AGS Airports, which operates Aberdeen and Glasgow airports, said all flights to and from London Heathrow had been cancelled for the rest of the day.

Edinburgh Airport also advised any British Airways passengers with flights to Heathrow not to travel to the airport. The airport added it has not been asked to take any diverted flights.

Budget airline Ryanair announced it will be launching eight “rescue flights” for passengers affected. The Irish airline said in a statement: “Ryanair will operate 4 extra flights between Dublin and Stansted on Friday afternoon as well as 4 extra flights on Sat morning.

EasyJet, which does not operate at Heathrow, said it will use larger than planned aircraft on key routes on Friday and over the weekend.

Several flights between the UK and Milan, Amsterdam, Edinburgh, Paris, Munich and Madrid will have A320 aircraft with a capacity for 186 passengers, instead of A319 aircraft which can only carry 156 passengers.

A Heathrow spokesperson said: “Heathrow is experiencing a significant power outage across the airport due to a large fire at a nearby electrical substation. Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored.

“To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23h59 on 21 March 2025. We expect significant disruption over the coming days and passengers should not travel to the airport under any circumstances until the airport reopens.

“We will provide an update when more information on the resumption of operations is available. We know this will be disappointing for passengers and we want to reassure that we are working as hard as possible to resolve the situation.”