A fire near London's Heathrow Airport plunged travellers around the world into chaos on Friday as more than 1,000 flights were diverted or cancelled.
Heathrow is closed for all of Friday after an overnight fire at an electric substation knocked out power at the airport. It has yet to be established when flights will resume but the disruption is expected to continue into Saturday at least.
About 120 flights already in the air were diverted to other airports, including in France, the Netherlands and Ireland. Other Heathrow flights are being cancelled or returning to their home airports.
We answer your questions on a day of travel chaos.
Will my Heathrow flight be running on Friday?
No planes are landing or taking off at Heathrow on Friday. The airport is telling people not to travel there as their flight will not be running.
Flights already in the air were either diverting to other airports, or turning back.
Are UAE flights affected?
Yes. Emirates cancelled 11 flights between Heathrow and Dubai on Friday. It said it is offering customers the option to rebook to other UK airports, or fly on another day.
Etihad cancelled four flights between London and Abu Dhabi. An earlier flight, EY61, was diverted to Frankfurt, Germany, which is about two hours from London by plane.
Are other London airports still running?
Yes. London's second-biggest airport, Gatwick, said it was operating as normal. The third-biggest, Stansted, said there were no changes to its flight schedule.
Low-cost airline Ryanair said it was adding four extra "rescue flights" to its schedule on Friday, flying between Dublin and London Stansted. Another four will run on Saturday.
How do I rebook my flight?
It depends on the airline but passengers were generally being told to sit tight and await updates.
Emirates said passengers could contact the airline if they booked directly, or otherwise speak to their travel agent. Etihad said it would notify customers of "changes to their itineraries".
Virgin Atlantic asked passengers not to phone due to high call volumes. The British Airways website was struggling under high demand.
Will flights resume on Saturday?
That is unclear. The airport said it is closed until midnight tonight but didn't give any timetable for what happens next.
Even if flights do resume it's likely there will be continued disruption because planes that got stuck on Friday will be in the "wrong" place for their schedule.
Airlines sound like they are preparing for more than one day of disruption. British Airways said it would update passengers on "travel options for the next 24 hours and beyond". Thai Airways said passengers on a Bangkok to London flight (TG910) on Saturday would have an "updated flight schedule".
How long could the disruption last?
John Strickland, an aviation consultant, reckons it will "run for several days". He said the closure on Friday was a "massive dislocation to have to recover from".
“Once an aircraft is in the wrong place with the crew, if you’re away from home you don’t have another crew to suddenly bring the plane and the passengers back," he said. "You’ve got to wait until that crew has taken its rest, which is always required after a duty period.
“We’re talking about several days worth of disruption to get the planes recovered and start using them again to move planned and disrupted passengers.”
Will I get food and a hotel?
If you are flying from the UK, or on a UK airline, airlines must offer you "care and assistance" if your flight is cancelled. This means they should give you food (or vouchers to buy food) and arrange accommodation if needed.
During major disruption, airlines might ask you to buy things yourself and claim the money back later. If this happens, the UK's Civil Aviation Authority says you should keep all your receipts and not spend "unreasonable" amounts of money, for example on luxury hotels.
For other flights it will depend on the country you are starting in. Within the European Union there are similar rules to Britain's about providing food and hotels.
Am I entitled to compensation?
Probably not under UK law, which says airlines do not have to pay compensation if there are "extraordinary circumstances" and the disruption is not their fault.
Rory Boland, the editor of Which? Travel, said that would be the case here. He said it might be worth checking the terms of your travel insurance to see if you could reclaim expenses such as car hire or parking fees.
How many flights are affected?
According to tracking website FlightRadar24 there were 679 flights scheduled to land and 678 scheduled to take off at Heathrow on Friday – a total of 1,357.
It said 120 flights already in the air when Heathrow closed were diverting elsewhere or going back to where they started.
Where are flights being diverted?
As of early Friday six flights had been diverted to Gatwick and three to Manchester, according to FlightRadar.
Outside the UK, seven had gone to Amsterdam, six each to Frankfurt and to Shannon Airport in Ireland, and three to Paris. Others never made it across the Atlantic, stopping for example in Washington or New York.
What caused the fire?
We do not know yet. London Fire Brigade and the Metropolitan Police were investigating.
Britain's Energy Secretary Ed Miliband said the National Grid had not seen "anything like the scale" of the fire before. "We’ve got to understand why this happened and we’ve got to work out what the lessons are for the resilience of our infrastructure," he said.
