Southwest Airlines said Thursday it will start its service to Hawaii from four cities in California: Oakland, San Diego, San Jose and Sacramento.

The Dallas-based carrier, which has not announced a start date, identified the cities a day after saying it would offer low-fare interisland service once its mainland-Hawaii operation is established.

“We’re on track with our plans to sell tickets this year” for the mainland-to-Hawaii routes, Southwest President Tom Nealon said in a news release.

Also Thursday, Hawaiian Airlines, which would compete directly with Southwest on the California routes as well as interisland service, responded to Southwest’s latest news.

“Southwest’s PR strategy has been to toss out tidbits without much detail, so it’s unclear what kind of service or operation they are committing to,” Hawaiian President and CEO Peter Ingram said in an email.

Ingram defended Hawaiian’s interisland service.

“We fly 170 B717 flights every day between our islands, from 5 a.m. to 10:15 p.m.,” he said. “We employ thousands of Hawaii residents — more than 1,000 mechanics, flight attendants, pilots and ground staff specifically for this part of our network — in careers that pay well, keep local talent in Hawaii and help our economy grow. Our operation is convenient and extremely punctual thanks to world-class employees who welcome our guests with unparalleled hospitality, so we are not afraid of competition.”

Ingram, who took over as CEO on March 1 after Mark Dunkerley resigned, also took issue with Southwest’s claim that its interisland flights would be priced lower than what is currently available and with Nealon’s characterization of current interisland fares as “very expensive.” Hawaiian controls more than 90 percent of the interisland market.

“We found Mr. Nealon’s statement about fares curious,” Ingram said. “The one-way fares for close-in travel tomorrow on one of our most popular routes — Honolulu-Kona — range from $85 to $195, while Southwest’s one-way fares for travel tomorrow from Austin-Houston — a flight of similar length – range from $233 to $270.”

Hawaiian, the state’s largest airline, saw its stock tumble 6.5 percent, or $2.65, to $38.25 Thursday after Southwest’s announcements.

Hawaii aviation historian Peter Forman said, “It’s not going to be easy to beat Hawaiian (on interisland serv­ice) because of Hawaiian’s excellent on-time performance, its very frequent flights, it is well liked and has a reasonable fare for the distance. Southwest’s business model depends on expanding the total number of travelers when they enter the market and that is primarily done by offering fares low enough to convince people not to drive their cars between certain destinations. But in Hawaii no one drives interisland and that strategy won’t expand that total number of travelers. Furthermore, Southwest’s strategy of selling most of its cabin at least two weeks before departure at a discount and charging a much higher rate in the final two weeks will not work too well in Hawaii because the people who can afford to pay the most — the tourists — are the ones that pay well in advance.”

New York-based airline industry analyst Bob Mann said, “Southwest Airlines will be a tough competitor, but likely limit its Hawaii service to its mainland points of dominance (West Coast, and longer term, to Phoenix and possibly Love Field in Dallas). Southwest is unlikely to ever mount a significant interisland pattern of service, more likely ‘round-robin’ patterns, for example, mainland-Maui- Kauai-mainland, to make better use of aircraft and crew resources.”