Hawai'i's two largest airlines have launched a new round of reduced fares for interisland travel.

After Aloha Airlines announced free return flights on select roundtrip interisland service, Hawaiian Airlines yesterday introduced a $39.50, one-way fare on first departures each morning from Honolulu to Kahului, Lihu'e, Kona and Hilo.

Under the Hawaiian plan, customers can book their flights on the airline's first scheduled service to Kona, Hilo, Kahului or Lihu'e and pay half price. Customers can book their return flights on Hawaiian's last scheduled departure of the day at the same $39.50. The flights must be booked at www.HawaiianAir lines.com. Customers have the option of purchasing their return tickets on peak-hour travel at full price.

"We're offering interisland travelers statewide more flexibility and fewer restrictions — this is a fare people can actually use," said Mark Dunkerley, Hawaiian's chief executive.

Aloha said it will match the Hawaiian offer.

Aloha launched the latest fare competition yesterday when it began offering free return flights for customers who booked flights on the airline's first scheduled service to the Neighbor Islands. The free return flight was for travel on the airline's last scheduled departure for Honolulu. Flights must be booked at www.alohaairlines.com.

Both programs are good for travel through Dec. 31.

The airlines' first flights typically are scheduled around 5 a.m. and last flights are around 8 p.m. Some restrictions may apply.

"It's an opportunity to give some people a break on flights that would otherwise have empty seats on them," said Thom Nulty, senior vice president for sales and marketing at Aloha.