Southwest Airlines aims to wrestle rights to serve the Houston-Mexico market from United

Southwest Airlines is once again taking aim at United in Houston, arguing that United should relinquish some of the route rights it holds to destinations in Mexico in order for Southwest to gain access to those markets.

During 2012 Southwest leveraged a campaign to launch international service from Houston Hobby, a move strongly opposed by United, which is the largest airline at Houston Intercontinental. Southwest prevailed and now aims to launch transborder flights from Hobby in late 2015.

Route authorities in some of Southwest's desired markets between Houston and Mexico are full, prompting Southwest to argue that designations held by both United and its regional affiliates in essence blocks new low-cost competition in the market. Ironically, ULCC Spirit worked to gain access to some of those markets prior to Southwest seeking approval for launch.