The city of Dallas has proposed a new plan for divvying up limited gate space at Love Field that could serve as a jumping off point for negotiations to end a long-running airport turf war between Southwest Airlines and Delta Air Lines.

The two airlines have been battling for more than three years over five daily flights to Atlanta that Delta operates at its rival's hometown airport, with a federal lawsuit over the dispute set to go to trial early in 2019.

The case centers around who should get access to gates at the city-owned airport, and how airlines should be chosen when there isn’t enough space to go around. Love Field is capped at a maximum of 20 gates — enough for about 200 daily departures — under the terms of the Wright Amendment Reform Act. It saw 7.9 million passengers in 2017.

Dallas city attorneys filed a motion last week that lays out a plan that would allow Delta, which doesn’t have the same lease rights as Southwest and the airport’s other tenant, Alaska Airlines, to operate at Love Field for at least three more years, with no guarantee it could stay beyond that time.

The new proposal doesn’t have sign off from the airlines yet, but it’s a concrete step forward for the city, whose lack of a clear accommodation policy had been blamed for contributing to the current legal mess.

Southwest paid to sublease the disputed gate from United Airlines in 2014 and has sought to evict Delta, comparing the Atlanta-based airline to an unwanted squatter. Southwest controls 18 of 20 gates at Love Field, operating about 180 daily flights.

Delta has been at Love Field since 2009 and has argued it should be allowed to continue operating because Southwest wasn’t fully utilizing the disputed gates when Delta made a request for accommodation. Delta has also argued the city has an obligation to provide a process for accommodating airlines wanting to serve the airport, even if they don’t have a preferential lease for gate space.

Instead of picking between the two airlines’ competing claims and fearing a lawsuit from whichever it decided against, the city filed a preemptive lawsuit against both, turning to the court for guidance on how to resolve the dispute.

In a 2016 preliminary injunction order, the judge presiding over the case said Dallas officials “wholly failed to craft any policy, let alone a clear one, setting forth how the accommodation procedure and process would work in reality.”

The city’s proposal put forward last week would establish a more formal process for evaluating requests by airlines to serve the airport that would weigh available space, the proposed destination and the number of passengers that would be served.

If space is available and the requesting airline is approved, that carrier would be able to operate for three years. After that point, the airline could request space again, a new airline could be given the space instead, or the gate space could be turned back to the leaseholder — currently either Southwest or Alaska.

The goal is to promote competition at the airport, said Dallas City Attorney Larry Casto.

“We need to [maximize] usage of that airport for the citizens and get them to places they want to go,” he said. “And in a competitive market, to the best of our ability, keep prices as low as possible.”

Casto said the three-year period was chosen because it seemed like a fair time period and would serve as a good starting point for negotiations.

Airlines will get a chance to weigh in on the proposal with their own motions to the court, but it appears the deal will need some more negotiation before its cleared for takeoff.

“Delta believes that the city’s proposed accommodation plan reduces, rather than promotes, competition at Love Field,” the company said in a statement.

Southwest acknowledged it’s evaluating the proposal but did not offer further comment.

City columnist Robert Wilonsky contributed to this report.