MIAMI — Southwest airlines may be starting service from Houston Hobby to Mexico City in 2015, if recent regulatory filings are any guide.

In a filing dated August 14, the carrier states that it does not oppose an application recently submitted by Skywest/United to serve the route (the filing is merely Southwest responding to the possibility of the two receiving it – sort of like open comments at a public meeting). If granted, it would expand the two’s service to the maximum two carrier designations allowed to serve the Mexican capital from Houston for two years.

Importantly, however, Southwest added that its tacit support will continue only up until the point that it decides it wants to run the route itself. From the filing: “Southwest urges the Department to put [Skywest/United] on notice that their authority and corresponding US carrier designations in this market are subject to being rescinded if Southwest were to actively seek competing authority to serve the Houston-MEX market.” The carrier added that it plans to do exactly that in 2015, right in the middle of the two-year grant to Skywest/United.

Thus Southwest utilized the filing to express concern over the idea, and remind the DOT that it is due the route should it chose to open it. It petitioned the DOT to recall that functional route monopolies aren’t a good idea: “To allow one carrier to occupy two or more designations under those circumstances would be plainly anti-competitive, as it would block a new entrant carrier from entering and competing on that route.” The carrier further argues that the intention of the designations was to provide multiple carriers opportunity to fly into Mexico (US-Mexico do not enjoy open skies).

Currently neither Southwest or its AirTran subsidiary offer international service from Houston Hobby. That is set to change in the fourth quarter of next year, however, as a new international terminal is set to open. Thus the routes out of Hobby could be some of, if not the, first wholly-Southwest international routes.

Presently the carrier has only been assuming former AirTran routes abroad, and has stayed mum on new route possibilities.