Hawaiian Airlines announced Monday that it’s launching direct service between Maui and Las Vegas in December on its Airbus 321neo, whose midrange capabilities have allowed the carrier to beef up service to smaller, secondary markets throughout the western United States.

The airline announced plans to begin four-times-weekly service between Maui’s Kahului Airport and Las Vegas’ McCarran International Airport on Dec. 15. The carrier will offer a special $199 one-way fare through Wednesday, and HawaiianMiles members will receive an additional 10% booking discount during the promotional period.

Hawaiian also announced sales for two other new A321neo routes: thrice-weekly nonstop service between Honolulu’s Daniel K. Inouye International Airport and Seattle-Tacoma International Airport starting Jan. 7, and seasonal winter service between Kahului Airport and Los Angeles International Airport from Dec. 14 through Jan. 5.

Hawaiian’s latest service announcements come as Southwest Airlines gears up to resume its Hawaii expansion, which was delayed by issues related to the Federal Aviation Administration’s lengthy Max plane grounding.

Gary C. Kelly, Southwest chairman and CEO, said during a July 25 second- quarter earnings call that the carrier would be “resuming our expansion without having to wait on the Max any further.”

Southwest is expected to soon launch service to Hawaii from Sacramento, Calif., and San Diego and interisland service for Lihue and Hilo.

Michael G. Van de Ven, Southwest chief operating officer, said during the earnings call that “Hawaii is off to a fantastic start” with strong demand and load factors that exceed the carrier’s system average.

“Although we’re early on in our expansion, our results so far are exceeding our expectations in every category. So, we’re now up to 14 daily flights, six in California to Hawaii, and eight interisland round-trip flights,” Van de Ven said.

He said Southwest is “obviously very eager to realize the cost efficiencies” of an eventual transition of Hawaii flights to Max planes.

“But we can fly the (737-800 Next Generation aircraft) to Hawaii as long as we need to while the Max is grounded,” Van de Ven said.

Use of the more fuel-efficient Max planes in Hawaii would heat up competition by allowing Southwest to add more destinations to its lineup of flights between Hawaii and the mainland.

There are roughly 17 cities Southwest serves west of the Rockies that it hasn’t connected Hawaii to yet. They include San Francisco, Burbank, Los Angeles, Ontario, Long Beach and Orange County, Calif.; Portland, Ore.; Seattle and Spokane, Wash.; Boise, Idaho; Reno and Las Vegas, Nev.; Phoenix and Tucson, Ariz.; Denver; Albuquerque, N.M.; and Salt Lake City.

But Hawaiian’s expanding fleet of narrow-bodied A321neos already has allowed it to “grow and transform” its North America network, said Brent Overbeek, Hawaiian Airlines senior vice president for revenue management and network planning, during a July 30 second-quarter earnings call.

“We’ve launched seven new routes with year-round service in the past 18 months. So just under a third of our North America routes are still relatively new and developing as expected, with encouraging unit revenue performance trends,” Overbeek said.

During the second quarter, Hawaiian launched A321neo service between Sacramento and Maui, growing its West Coast-to-Maui network to eight routes. It also took delivery of one A321neo in the second quarter and said that it remains on schedule to receive four more this year.

Hawaiian reported on the second-quarter earnings call that the carrier “by this time next year” would have its “18th A321neo, the final aircraft in our current A321neo order book on hand.”

Last year the carrier had to cut summer flying due to delays by Airbus in delivering the more energy-efficient and quieter A321neos.