The special fares, which are available on all go! flights, were immediately matched by competitors Aloha Airlines and Hawaiian Airlines.

Go!, a unit of Phoenix-based Mesa Air Group, said go!Express will begin operations on April 16 with 12 daily flights between Honolulu and Lana'i, Moloka'i and Kapalua.

The new venture, which will fly Cessna Grand Caravan aircraft, is in partnership with Kailua-Kona-based Mokulele Airlines.

"This new go!Express partnership will extend our network and offer go!'s market-leading low fares to more travelers throughout Hawai'i," said Jonathan Ornstein, Mesa's chief executive officer.

The $19 fares go on sale at midnight tonight and are good for travel through April 23. Tickets must be purchased by March 23.

Restrictions apply to the go! fares, and go! did not specify how many $19 tickets would be available.

When go! last announced the $19 fares in September, they were immediately matched by Aloha and Hawaiian.

Prior to that, go! offered $19 fares when it opened for business on June 9. Hawaiian matched those fares while Aloha countered by giving away 1,000 tickets.

Go! touched off a price war when it opened for business in Hawai'i on June 9.

Aloha executives have said that all three interisland carriers are losing money when they sell interisland tickets below $50.