The US Department of Transportation (DOT) has tentatively granted antitrust immunity to the proposed Delta Air Lines-WestJet transborder joint venture (JV), but with conditions that the carriers must accept.

“The department is proposing, as a condition of approval, that the carriers remove Swoop, an ultra-low-cost carrier affiliate of WestJet, from the alliance, and divest 16 takeoff and landing authorizations (slots) at New York City’s LaGuardia Airport (LGA),” DOT said in a statement.

“The department is also proposing other conditions, including requiring WestJet to provide interline access to select carriers flying to Canada, and reviewing the proposed alliance in five years’ time.”

DOT noted that its “show cause order” is a first step in the approval process and interested parties have 14 days from Oct. 23 to submit public responses before the department makes a final decision.

The Delta-WestJet agreement deepens the existing codeshare partnership between the US and Canadian airlines. The companies plan to expand codesharing, more closely align frequent flyer programs, jointly coordinate schedules and work together on cargo operations.