A crackdown on hidden air travel costs comes into force across Europe this weekend.
Airlines are obliged from Saturday to make clear in their advertising the price passengers actually pay - including all taxes and airport charges which are sometimes hidden in the small print or not mentioned at all.
The new EU rules also ban airlines from adding "optional" additional charges without passengers' express consent. And different air ticket prices for the same journey booked in different EU countries will also be outlawed.
The latest rules come a year after a 15-country survey coordinated by the Commission into misleading advertising and unfair practices on airline ticket websites.
The survey showed more than 50% of the sites carried confusing prices and contract terms, and Commission officials have now threatened legal action against offending companies unless they improve their website information.
The new rules in force tomorrow also give national authorities standard powers to prevent airline bankruptcies and enforce quality and safety standards.
Criteria for the granting and monitoring of airline operating licences will be stepped up to "the same level of severity" in all EU member states, the Commission said.
EU transport Commissioner Antonio Tajani said the liberalisation of the EU air transport sector in 1997 had been a success, with expansion in the industry and healthy competition offering more routes and lower prices, but the real cost of air travel had to be made clearer in advertising.
He went on: "Fair competition is the key to success - with price transparency, passengers will know in advance how much they are going to pay and will be able to make informed choices".
A Commission statement said: "From now on, ticket prices will have to be published inclusive of all taxes and charges.
"Also, passengers will be able to see the breakdown of the different categories of costs making up the final price: tariff, taxes, airport charges and other fees.
"Travellers will also benefit from precise information on actual prices, making it possible for them to avoid misleading advertising and compare prices more easily."