When will Heathrow airport fully reopen?
21 March 2025, 13:13 | Updated: 21 March 2025, 22:42
Heathrow Airport has confirmed when it will resume flights following chaos caused by a fire.
Listen to this article
Loading audio...
Heathrow has now been able to safely land the first flights after severe delays and diversions this afternoon, with plans in place to return to a full service by Saturday, the airport's boss has confirmed.
Repatriation and relocation of aircraft will be prioritised, the airport said.
The first plane to touch down at the airport took place just after 6pm on Friday, with the inbound BA jet landing at Heathrow after departing from Gatwick earlier in the afternoon.
A statement read: "Our teams have worked tirelessly since the incident to ensure a speedy recovery. We’re now safely able to restart flights, prioritising repatriation and relocation of aircraft.
"Please do not travel to the airport unless your airline has advised you to do so.
"We hope to run a full operation tomorrow and will provide further information shortly.
"Our priority remains the safety of our passengers and those working at the airport. We apologise for the inconvenience caused by this incident."
Airport bosses have warned of "significant disruption" over the coming days and told passengers not to travel under any circumstances until it reopens.
Earlier, Heathrow announced that it would be closed for all of Friday as it dealt with the incident.
"Due to a fire at an electrical substation supplying the airport, Heathrow is experiencing a significant power outage," a statement said.
"To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23h59 on 21 March.
"Passengers are advised not to travel to the airport and should contact their airline for further information. We apologise for the inconvenience."
There was a "cross-government call" on Friday morning to deal with the immediate aftermath of the fire, a No10 spokesman said.
Heathrow closure: What we know so far
Firefighters battle blaze at substation in Hayes
He added: "The Department for Transport is working closely with Heathrow Airport, Nats (National Air Traffic Services) and all key operators to understand the situation and ensure a quick resolution so that the airport can reopen and flights resume as quickly as possible, and clearly we will do everything we can to support those affected and get things moving again."
When will the power be back on?
Professor John Loughhead, electrical engineering expert at the Institution of Engineering and Technology (IET) said: “To restore power, supply companies may be able to route power to Heathrow through an alternative circuit, although it seems this is not easily done or may not be possible, or any damaged equipment will need to be replaced to get the substation back into service.
“To determine the original cause will mean examination of the damaged equipment and operating records to judge the sequence of events leading to the fire which may be obvious or require some time to work out.”
Graham concluded: “The Civil Aviation Authority has rules that govern the impact of power loss on airport operations, which includes consideration as to how long the loss of some, or all, power at an airport is expected to last. Airport operations can also be affected by the consequences of a major incident in the vicinity of the airfield or flight paths, for example smoke affecting flights.”
The National Grid said the substation network had been reconfigured to restore power to the parts of Heathrow Airport connected to it on an interim basis.
"The network has been reconfigured to restore all customers impacted, including the ability to resupply the parts of Heathrow airport that are connected to North Hyde," a spokesperson said.
As of Friday afternoon, some power had returned to Terminal 4, with lights in the main building and car park lifts operational again.
Why has this fire happened?
“Fires do occasionally, but not frequently, occur at substations and can have various causes - from electrical short circuits to failures in transformers,” explained Prof Loughhead.
“It's not stated what caused this one and it may take a while for what happened to be determined. A fire within a substation area can damage switchgear, transformers, measurement and control equipment, and cables.
"Fires are not unprecedented but also not frequent. If they damage equipment any user 'downstream' of the substation will lose all power. In this case Heathrow just happens to be the key user, although it seems other users are also affected.”
The law requires that all electrical installations are maintained in order to be safe for continued use. This applies to electrical substations which should be regularly checked. As part of this, records will have been kept of testing and inspection and, for example, thermal imaging cameras will have been used to make sure connections aren’t overheating.
Maintenance work will look to diagnose possible failures of equipment and then any required repair work can be carried out. For this situation, the investigation will look at the history of the equipment, such as the manufacturer’s data from when it was manufactured. The investigation will be far reaching, and every aspect will be looked at to ascertain what has happened. It is very unusual for one incident to cause the entire shut down of an entire site like Heathrow airport.
Counter terror police are investigating the incident and there is currently no suggestion of foul play. However, it will take "a long time" to be sure.
Q&A
What flights are covered by UK consumer law?
Flights operated by an airline departing from a UK airport, flights operated by a UK or EU airline arriving at a UK airport, or flights operated by a UK airline arriving at an EU airport.
What options do passengers have?
They will have the choice of being re-booked on to an alternative flight, or accepting a refund.
What does re-booking involve?
If a flight is cancelled, airlines are required to get you to your destination if you still want to travel.
Most will book you on to another of their flights, but you may be entitled to travel with another airline or by an alternative mode of transport if it will get you to your destination significantly sooner.
Passengers doing this are often required to purchase their own tickets and submit a claim to their original airline for reimbursement.
What assistance should be provided by airlines?
Airlines have a duty of care to stranded passengers.
This includes a reasonable amount of food and drink (often via vouchers), a means to communicate (often by refunding the cost of phone calls), and accommodation and transfers if an overnight stay is required.
What happens in reality?
Airlines often fail to provide this assistance during major disruption because they are overwhelmed by requests and there are not enough available rooms in local hotels.
The Civil Aviation Authority (CAA) says in this scenario, passengers can organise their own assistance and claim the costs back from the airline by submitting receipts.
Does that mean I should book a luxury hotel suite and order champagne?
Airlines are unlikely to reimburse you for that. The CAA advises passengers not to "spend more than is reasonable".
How long must assistance be provided?
Until your flight takes off or you accept a refund after deciding not to travel.
Am I entitled to compensation for a delayed flight?
Not for Friday's incident, as the fire was outside airlines' control.
