JetBlue Airways Corp. and Spirit Airlines Inc. asked a federal court Tuesday to fast-track its appeal of a ruling that blocked their proposed $3.8 billion combination on antitrust grounds. 

Without expedited review, the appeal probably won’t be decided before the July 24 deadline for JetBlue’s purchase of Spirit to close, the carriers said in a filing with the federal appeals court in Boston. They asked for a briefing schedule that would begin next month.

A lower court judge ruled on Jan. 16 that the purchase couldn’t proceed because it would limit options for price-conscious travelers and raise fares. That decision should be reversed because it ignores benefits from the combination for the majority of the flying public, among other reasons, the airlines said. 

Spirit shares were up nearly 6% in pre-market trading, while JetBlue was down by around the same percentage. JetBlue said Tuesday that it expected revenue to fall 9% this quarter from last year and that it was weighing deeper cost cuts.

JetBlue warned Spirit on Jan. 26 that the merger agreement could be terminated on or after Jan. 28 because certain conditions may not be satisfied by dates specified in the fine print. Spirit countered with a filing of its own, saying the terms of the deal remain in effect, and there’s no basis for JetBlue to walk away.