(Reuters) -JetBlue ( JBLU ) and United Airlines have cleared a review of their planned Blue Sky partnership by the U.S. Department of Transportation (DOT) allowing them to proceed with the implementation, the companies said on Tuesday.

The two companies in May unveiled a partnership that would allow travelers to book flights on both carriers' websites, while interchangeably earning and using points in their frequent flyer programs.

Spirit Airlines in June had urged the U.S. transportation body to reject the collaboration between the two carriers, saying it was anticompetitive and would prompt other large carriers to pursue similar deals.

JetBlue ( JBLU ) and United said that Blue Sky would begin introducing new customer benefits starting in fall 2025, rolling them out in phases.