Travelers scheduled to fly into, out of, or connect through London’s normally bustling Heathrow Airport (LHR) on Friday, March 21, were in for a rude awakening. The entire airport closed for most of the day due to what airport authorities described as a “fire at an electrical substation supplying the airport,” which resulted in “a significant power outage” at the hub.
Due to safety concerns, Heathrow made the decision to shut down the entire airport. At press time, Heathrow had begun to restart flights, according to a notice to travelers on its website.
“To maintain the safety of our passengers and colleagues, Heathrow will [be] running a reduced operation prioritizing repatriation and relocation of aircraft,” the airport stated in its most recent update.
There were 1,334 flights scheduled to either take off from Heathrow or arrive at Heathrow on Friday, representing nearly 300,000 air travelers, aviation analytics company Cirium reported. The majority of those flights—51 percent of which are operated by British Airways—had been canceled. Most were flights to or from New York’s John F. Kennedy International Airport.
There are an additional 1,219 flights scheduled to arrive at or depart from Heathrow on Saturday.
At 11:23 p.m. on Thursday, March 20, the London Fire Brigade reported that it received dozens of calls about a fire at a high-voltage substation near Heathrow.
“The fire involved a transformer comprising of 25,000 liters [6,600 gallons] of cooling oil fully alight. This created a major hazard due to the still live high-voltage equipment and the nature of an oil-fueled fire,” the brigade reported.
Firefighters worked overnight to contain the fire, which initially left 67,000 households without power, in addition to two Heathrow terminals, Terminal 2 and Terminal 4.
What the airlines are offering travelers
With thousands of passengers facing canceled flights, the airlines are responding with change fee waivers. Delta Air Lines has issued a fare and change fee waiver on all flights to, from, or through Heathrow happening on or before March 26.
“Check flight status frequently for up-to-the-minute information about your flight plans,” Delta said in a statement.
“When rebooked travel occurs on or before March 26, 2025 in the same cabin of service as originally booked, the fare difference will be waived,” Delta stated, noting that a fare difference may apply if the fare class changes for the new booking.
United Airlines has issued a fare and change fee waiver due to the Heathrow closure, too, for flights purchased on or before March 20, to or from Heathrow.
“If your flight is affected, here are your options,” United stated. “You can reschedule your trip and we’ll waive change fees and fare differences. But, your new flight must be a United flight departing between March 20, 2025 and March 28, 2025. Tickets must be in the same cabin and between the same cities as originally booked or one of the following: Amsterdam, NL (AMS); Brussels, BE (BRU); Paris, FR (CDG); Edinburgh, GB (EDI).”
American Airlines informed customers traveling to, through, or from Heathrow that their change fee will be waived for travel purchased by March 20, 2025, that was scheduled to take place March 21 or March 22, 2025. Changes must be booked by March 22, 2025, the airline stated, and travel must be completed within one year of original ticket date.
What to do if you’re flying on a rewards ticket? As Adam Morvitz, travel expert and CEO of Point.me, a search engine for points and rewards, told Afar after the Crowdstrike outage last year, “You’re in the same boat as cash ticket holders.” Said Morvitz: “While airlines will rebook you automatically, calling customer service might yield better options. Note that airlines won’t cover extra costs like hotels or meals, so plan accordingly.”
Airports and routes that are hardest hit
Heathrow is the busiest airport in Europe, according to global travel industry data provider OAG, with nearly 4.3 million passengers scheduled to arrive or depart from the hub in March 2025 alone.
The most impacted routes caused by Friday’s closure were from New York’s JFK, with 4,500 air travelers scheduled to fly to, from, or through Heathrow on Friday, followed by Dubai with 3,000 impacted travelers.
Other hubs with high volumes of flights scheduled for Heathrow on Friday include Dublin, Frankfurt, Doha, Munich, Los Angeles, Madrid, and Delhi.
How long will the problem last?
Flight cancellations and disruptions resulting from Heathrow’s closure could last well into the weekend.
“The sheer volume of flights impacted today means that aircraft, crew, and passengers are not where they are supposed to be. And that’s just for cancellations and diversions in the last 12 hours,” said Cirium spokesperson Mike Arnot. “It will continue to build on Friday, with passengers in London or connecting through London impacted, along with those in every other city waiting to get to London or connect there. It will take several days for the airlines to reset and recover passengers. There simply aren’t enough planes and seats to recover quickly.”
He added that the disruptions will also vary by airline. “Some large airlines might fare better given the frequency of flights and volume of available seats they have. If you’re a passenger or were about to travel, I could see Friday’s disruption impacting flights until at least Monday night. And likely further into next week,” said Arnot.
What travelers should do
First off, travelers should know their rights. “When flights are delayed and canceled, we expect airlines to minimize the overall impact on you by keeping you informed and looking after you. Your airline is required to offer you the choice of a refund or find you an alternative flight. Re-routing should be at the earliest opportunity or at a later date at your convenience, subject to availability,” the U.K. Civil Aviation Authority said in a statement about the Heathrow closure.
Your flight is covered by U.K. legislation as long at it is a United Kingdom, European, or international carrier departing from Heathrow, or a U.K. or EU carrier arriving at Heathrow. The only flights not covered are non-U.K. or non-EU carriers arriving at Heathrow.
“If your airline is unable to proactively offer you care, or offer suitable replacement flights, we expect it to promptly reimburse you for the costs you incur making your own arrangements. Make sure you keep receipts and avoid incurring excessive costs,” the U.K. Civil Aviation Authority advised.
The agency noted that airlines are required by law to get travelers home and to look after them while they wait, by providing meals and hotel accommodations.
Morvitz provides a list of handy tips for travelers with upcoming flights.
- Stay ahead of the game: The points pro advises travelers not to wait for updates from the airline. “Keep an eye on your flight status . . . if there’s a problem, make changes ASAP.”
- Use the airlines’ travel waivers: All major airlines are offering fee waivers right now, including for reward tickets. Go ahead and take advantage to change your flight.
- Explore back-up options: Research alternative flights and have a backup at the ready.
- Double-check your rebooked flight: If you changed your flight, double-check the status of the new flight before heading to the airport—the cascade of delays and cancellations could also impact the new flight.
- Manage expenses: Be prepared for added expenses for hotels or meals that may or may not be covered by the airlines. Check your credit card and travel insurance (if you have it) policies for coverage and benefits.
