WOW Air confirmed it had cancelled all flights and ceased operations on Thursday (March 28).
The Icelandic budget carrier was unable to secure investment to keep the airline in operation.
Passengers have been advised to make alternative travel arrangements.
In the UK, WOW operated from Gatwick, Stansted and Edinburgh airports.
Wizz Air has launched rescue fares, while the CAA, Abta, WOW itself and Which? have all issued guidance.
Here is everything you need to know about the WOW air failure:
Wizz Air: Wizz Air has announced rescue fares for passengers who were due to travel between Reykjavik and either Gatwick or Stansted with WOW from £74.99, valid for travel through May 10 and subject to availability on each flight.
Rescue fares must be booked by April 7. Customers will have to provide evidence of valid WOW air bookings affected by its collapse. Wizz flies four times a week between Luton and Reykjavik on Mondays, Wednesdays, Fridays and Sundays.
Icelandair: Icelandair is offering support for any passengers stranded in Europe or North America with a WOW ticket.
"We are offering WOW Air passengers that have a return ticket home special discounted economy standard fares from select destinations. These fares will only be available for passengers that have a ticket home with WOW Air between March 28 and April 11.
"Passengers must call our dedicated hotline to book. If currently in Iceland or Europe, call +354 50 50 200; if in North America, call +1 (800) 223 55 00." For more information, visit icelandair.com/getmehome.
Norwegian: Norwegian will start offering repatriation fares to support affected WOW Air passengers on Friday (March 29).
Repatriation fares will be available at 25% discount on economy net fares, subject to availability.
The fares are available for travel until April 8. WOW Air customers must be able to show a valid WOW Air booking on the following routes in either direction:
Customers should visit www.norwegian.com/uk/help-contact for more details.
EasyJet: EasyJet says it is working to assist affected passengers booked on flights between Keflavik and Stansted. It is offering a dedicated rescue fare of £110, including hold baggage, to enable affected customers to travel with easyJet between Luton or Gatwick and Keflavik through April 14. Tickets must be issued on or before April 7 2019.
Passengers should contact easyJet customer services on +44 (0) 330 365 50302 to book rescue fares, available upon presentation of their original WOW booking reference.
Virgin Atlantic: Virgin is offering WOW passengers stranded in the UK, US and Canada discounted fares to get home. Anyone who needs help should call 0344 874 7747 in the UK or +1 800 862 8621 in the US.
Bookings can be made through to April 6 for travel up to April 30. To access the special fares, customers will need to show proof of their WOW Air booking for the same origin and destination, named customers, and March/April travel dates.
WOW Air has ceased operation. All WOW Air flights have been cancelled.
Passengers are advised to check available flights with other airlines.
Some airlines may offer flights at a reduced rate, rescue fares, in light of the circumstances.
Information on those airlines will be published when it becomes available.
Information is available from the WOW Air website, Icelandic Transport Authority, Keflavik airport and other relevant airports.
Options available to customers due to travel with WOW will depend on what, and how, they booked.
The CAA will publish a negative response letter shortly.
Consumer watchdog Which? claims WOW was continuing to sell fares at 7am on Thursday, two hours before the airline ceased operations.
“Passengers will quite rightly be appalled WOW Air was still selling tickets right up to the moment it collapsed knowing full well that any tickets sold would likely not be worth the paper they are printed on.
“You will need to check if you booked your flights as part of a package as this will mean you are Atol protected and will be entitled to your money back.
“If not, you may still be able to claim through your travel insurance or card issuer but it will depend on your circumstances. You can visit which.co.uk for more advice on your rights.”
WOW's collapse comes just days after fresh discussions over the airline’s future got under way on Tuesday (March 26), the best part of five months after initial talks over a potential sale of WOW became public.
Last November, Icelandair announced it had agreed to acquire the low-cost carrier for a reported €18 million, only to pull out of the deal a fortnight later.
US investor Indigo Group came in for WOW after Icelandair walked away. However, WOW confirmed last week talks with Indigo had broken down, and that it had resumed discussions with Icelandair.
Talks between the two Icelandic carriers reopened last Wednesday (March 20) but Icelandair confirmed on Sunday (March 24) it had decided not to invest.
WOW proceeded to consult bondholders over a voluntary restructure, including the prospect of converting existing debt into equity, a move which took a major step forward on Tuesday (March 26).
“Bondholders have formally approved to convert their bonds into equity, and formal discussions with investors have commenced to fund the company,” said the airline in a statement.
“This is an important milestone in financially restructuring the company and secure the long-term sustainability of WOW Air.”
Two days later, the airline announced it had cancelled all flights and ceased operations.
WOW Air flies from Gatwick, Stansted and Edinburgh to Iceland and serves North America and continental Europe.
Its operations are built around Reykjavik’s emergence as a transfer hub, but incurred heavy losses in the year to June 2018 as it sought to expand its operations.
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