Alaska Airlines upgraded its equipment on its San Francisco to Phoenix route to compete with other carriers.
The airline likely used smaller regional aircraft to test the route's performance, but demand has remained steady.
The carrier will schedule flights on the Boeing 737s for the next few months, indicating their presence on the route is here to stay.
Seattle-based Alaska Airlines quietly boosted capacity on flights between San Francisco and Phoenix earlier this year. The carrier upgraded the equipment on the route from smaller regional aircraft to larger mainline Boeing 737s.
It comes as Alaska has worked to simplify its fleet over the last couple of years. The change puts the airline head-to-head with four other carriers that operate larger narrowbody aircraft on the route.

For the first time
According to aviation data and analysis provider Cirium, Alaska began deploying the Boeing 737-900, -900ER, and MAX 9 between its hub at San Francisco International Airport (SFO) and Phoenix Sky Harbor International (PHX) Airport in January. It is the first time mainline aircraft have operated the route since the airline introduced it in the Summer of 2020.

Alaska’s wholly-owned subsidiary, Horizon Air, and regional contractor SkyWest Airlines have been responsible for the flights, utilizing the Embraer E175. With each aircraft accommodating 76 passengers, Alaska was able to offer more than 2,000 seats per month on the route, depending on the amount of frequencies. However, with less capacity than its 737s, the airline likely used the E175 to gauge how well the route would perform during the first few months.