A new EU accord with the United States for wide checks of air passengers in the fight against terrorism was agreed to by the European Commission, despite fears in some quarters it infringes privacy rights.
It has been condemned by the European Parliament, which has threatened to mount a legal challenge.
Commission spokesman Mr Jonathan Todd told a news conference that Brussels had negotiated enough guarantees to protect people's privacy but did not believe it would be able to win more concessions from the US authorities.
"Therefore the alternative to not taking a decision would be legal uncertainty and potential chaos for passengers and for airlines," he said.
Some data viewed as too personal, such as meal orders or special requirements that could reveal someone's religion, race or health, would not be transferred or would be deleted by the US authorities, Mr Todd added.
But credit card numbers and, possibly, mobile phone numbers, would be transferred, he said.
"The data will be used only to combat and prevent terrorism, terrorism-related crimes and serious crime, including organised crime of a trans-national nature," he said.
Airlines, fearful of fines for failing to hand over data, have already been co-operating with US authorities.
Mr Todd said guarantees and concessions from US authorities included the transfer of 34 categories of information, compared with a possible 60 which airlines collect. The European Parliament wanted only 19 to be shared.
The information would only be sent by the US Customs and Border Protection with other agencies on a case-by-case basis rather than in a general fashion.