SkyWest Airlines will begin flying six West Coast routes for its newest customer, Alaska Airlines, next month, and in the process, gain five more regional jets for its fleet.

Starting May 14, St. George-based SkyWest will fly the routes now flown by Horizon Air, Alaska's sister airline.

SkyWest will operate the routes from Seattle and Portland with 70-seat Bombardier CRJ700 regional jets leased from Horizon.

SkyWest already operates regional flights for Delta Air Lines, United Airlines and AirTran. Alaska becomes SkyWest's fifth airline partner.

The fixed-fee contract, also known as a capacity purchase agreement, will run for seven years, said Mike Kraupp, SkyWest's vice president of finance, on Wednesday.

"We add another partner and have another capacity purchase agreement that is profitable from Day One," Kraupp said.

Under the agreement, SkyWest will operate and maintain the aircraft, while Alaska is responsible for scheduling, pricing and marketing the flights.

The CRJ700s will be painted with Alaska Airlines colors, which include the face of an Inuit on the tail.

Horizon is standardizing its fleet, which is why Alaska decided to hire SkyWest to operate the routes to Southern California and Portland. Instead of a mix of CRJ700 jets and Bombardier 76-seat Q400 turboprops, Horizon is moving to a fleet made up solely of slower but more fuel-efficient Q400s, Alaska spokeswoman Bobbie Egan said.

The destinations are served by Horizon's CRJ700s. Switching to Q400s would add extra flying time, so it made sense to hire SkyWest to fly the routes and transfer the CRJs, Egan said.

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