Delta has removed its schedule and fare information from over a dozen sites, including TripAdvisor Inc., Hipmunk Inc. and, saying it didn’t authorize the sites to use its data, according to a report to be released on Wednesday by the Travel Technology Association, a trade group for the sites. The group said Delta’s move is part of a broader push by airlines to restrict how—and whether—sites can use their fare and schedule data. The group says carriers including American Airlines Group Inc. and United Continental Holdings Inc. have recently adopted policies allowing them to limit how the sites use their data. The spat marks the latest chapter in the struggle for control over airfare searches and seat purchases online. Carriers increasingly are pushing fliers to their own sites, partly to improve sales of add-on products such as extra legroom and frequent-flier points. And they have butted heads with the travel sites over booking fees. In a dust-up last August, American temporarily withdrew its flight information from sites operated by Orbitz Worldwide Inc. Get the full story at The Wall Street Journal and CNNMoney Read also Travel Technology Association's study "Benefits of Preserving Consumers’ Ability to Compare Airline Fares" (PDF 3.4 MB)