Spirit Airlines’ possible transborder flights from Houston could dampen Southwest's ambitions

Armed with approval to introduce service from Houston Intercontinental to three markets in Mexico, Spirit Airlines has the potential to create a new layer of competitive dynamics in the market as Southwest prepares to add international flights from a new terminal at Houston Hobby in late 2015.

Spirit has not formally announced the launch of new international flights from Houston Intercontinental; but its moves to secure authority for service to Mexico show that it aims to position itself as a formidable competitor to Southwest and legacy airlines alike.

Spirit's work to gain approval for the new service to Mexico is within the framework of a bilateral that limits the number of airlines on specific routes, so Spirit may be attempting to secure a place in key leisure markets as Southwest plots its international strategy from Houston.