Heathrow, the U.K.’s biggest airport and a global travel hub, will remain closed until 11:59 p.m on Friday, the airport said, with disruption expected to affect hundreds of flights. According to flight tracker site Flight Radar, 679 flights were scheduled to land at Heathrow on Friday, while 678 flights were scheduled to take off from the airport. British Airways advised customers not to travel to the airport until further notice. A fire at an electrical substation caused the closure of London’s Heathrow Airport on Friday causing major travel disruption around the world. Heathrow, the U.K.’s biggest airport and a global travel hub, will remain closed until 11:59 p.m on Friday, the airport said, with disruption expected to affect hundreds of flights. According to flight tracker site Flight Radar, 679 flights were scheduled to land at Heathrow on Friday, while 678 flights were scheduled to take off from the airport. Here’s what airlines have been telling passengers due to fly into or out of the airport: British Airways British Airways advised customers not to travel to the airport until further notice. “This will clearly have a significant impact on our operation and our customers and we’re working as quickly as possible to update them on their travel options for the next 24 hours and beyond,” a statement said.   “Where possible, we’re redirecting inbound flights already on their way to Heathrow to other UK airports.” Virgin Atlantic A spokesperson for Virgin Atlantic told CNBC that the closure of Heathrow was having “a significant impact on our flying program both into and out of Heathrow.” “All Virgin Atlantic arriving and departing flights are cancelled until 21:30 on 21 March, with the rest of today’s schedule currently under review,” they said in an emailed statement. “We kindly request that all customers do not travel to Heathrow or their scheduled departure airport, or contact our customer centre at this time and instead check their flight status at virginatlatic.com.” Airborne flights operated by Virgin Atlantic are currently being diverted to other U.K. airports or returning to where they took off. The airline said it would email affected customers with rebooking details, but said that due to availability, some customers may be booked onto flights on a different date or need to travel to or from a different airport. Passengers whose flight was cancelled and no longer wished to travel would be entitled to a refund. Lufthansa Lufthansa told CNBC it had cancelled all flights due to arrive at and depart from Heathrow on Friday. “Passengers affected by the flight cancellations have been rebooked on other flights and informed about it,” a spokesperson said via email. “This requires that contact details, such as email or phone number, are included in the booking.” Singapore Airlines A spokesperson for Singapore Airlines (SIA) said a number of its flights had been impacted by the disruption. Flight SQ322, which left Singapore on Thursday, was diverted to Frankfurt, while flight SQ306, which took off from Singapore on Friday, was diverted to Charles de Gaulle Airport in Paris, France. Another flight that took off on Friday returned to Singapore. Flight SQ318 out of Singapore has been canceled, the spokesperson added, as have many of the airline’s planned departures out of Heathrow. “SIA will provide all necessary assistance to the affected passengers, including providing hotel accommodation, and reaccommodating them on alternative flights or land transport,” the spokesperson said. “Other SIA flights between Singapore and London Heathrow may be affected.” Emirates Emirates said on Friday that it had canceled six flights into and out of Heathrow. “Passengers connecting onto the flights to London Heathrow will not be accepted for travel until further notice at the point of origin,” the airline said in a statement. “We’re monitoring the situation closely and will update our customers as the situation develops.” Travelers due to fly in or out of Heathrow with Emirates can rebook to travel to other U.K. airports, or travel on a later date, the airline said. Cathay Pacific  Cathay Pacific said flights CX239 and CX253 from Hong Kong to London on 21 March have been canceled. “All Cathay flights from London to Hong Kong on 21 March have also been canceled,” it said in a statement. “We are assessing the situation and will keep our customers informed with the latest updates.” United Airlines United Airlines said seven of its flights had been diverted or returned to their originating airports due to the closure, adding that all flights to London Heathrow on Friday had been canceled. “We are working with our customers to offer alternative travel options,” the carrier said in a statement. Swiss Swiss said it was canceling all flights from Zurich and Geneva in Switzerland to Heathrow on Friday, affecting almost 3,000 customers. “As a precautionary measure, all flights from Switzerland to and from London Heathrow have been closed for sale tomorrow, Saturday, March 22. SWISS deeply regrets the inconvenience this has caused passengers. We hope that the situation at London Heathrow will return to normal as soon as possible,” the airline said. Qatar Airways Qatar Airways said Friday that seven of its flights had been affected by the closure of Heathrow. “Qatar Airways is working closely with LHR airport officials. Passengers impacted due to above will be taken care of by our customer care and airport teams,” it said. Aer Lingus Irish carrier Aer Lingus said Friday that all of its flights into and out of London Heathrow were being canceled until further notice.   It advised passengers due to take one of its flights to monitor their flight status and check information about the operation of their departure airport. “If your booking was made through a third party (such as a travel agent, online agency, or another airline), please be aware that they may receive flight status updates on your behalf,” it said. “If your travel itinerary also includes a booking with another airline, please contact the airline directly for your options.” ...read more read less