MIAMI — Last month, United Airlines stopped flying between Cleveland and Phoenix. This route was the only mainline route United cut from Cleveland when it de-hubbies the city.

For several years, United (and its merger partner Continental) had a monopoly on this route. Now one month after the carrier stopped flying its one daily round trio flight between the two cities, three airlines have already announced plans to begin flying between these two cities.

Now, Frontier, Southwest, and US Airways enter the picture.

Frontier Airlines announced plans to launch three weekly flights (Mon., Wed., and Fri.) between these cities in March, and it flew its inaugural flight last week. The carrier operates a Airbus A320 on this route with 188 seats. When this route was announced, the route was only a summer seasonal route, but the carrier will resume service again in November.

US Airways announced plans to begin flying between Phoenix and Cleveland last month. The carrier will fly one daily round trip flight October 3, and it will operate a Airbus A320 with 150 seats on this route.

Southwest has not made any official announcements about starting flights between Cleveland and Phoenix, but in its weekly schedule update, the carrier’s reservation system shows that it will start nonstop flights between the two cities on December 29. The airline will operate daily flights until January 4, 2015 which is when its schedule ends. It’s not clear if this route is only seasonal or will be year round. Either way, it appears that Southwest sees potential in this market. The carrier will be operating a Boeing 737-800 with 175 seats on this route.

During the first quarter of 2013, the peek amount of passengers on this route was 350 per day. Many of the 350 were connecting passengers as Cleveland was still a hub for United at the time.

By the end of the year, there will be 513 seats available on Mondays, Wednesdays, and Fridays. On all of the other days there will be 325 seats available.

This route may be slightly tough to pull off with three airlines competing. Although, Phoenix is a focus city for Southwest and a hub for US Airways. The carriers’ large operations will allow Phoenix to be a connecting point for onward connections to other destinations in the southwest region of the U.S.. However, a Frontier only flies to Denver from Phoenix.

Who will survive? I guess we’ll have to wait and see.