Hawaiian said it will stop selling coupons for interisland flights on Monday. Existing coupons will be honored until their expiration dates through December.

The airline also plans to switch to electronic tickets for interisland and Mainland flights. Travelers who want paper tickets will need to pay $25 extra.

The end of the Hawaiian coupons means travelers can no longer walk up to the ticket counters and hop on a flight at a predictable price.

The convenience of coupons, which have been sold in books and redeemed on any flight with available seats, made the program widely popular among commuters, frequent business travelers, companies that bought coupons in bulk and vacationers who could buy coupons from travel agents for spur-of-the-moment island trips.

At Aloha Airlines, spokesman Stu Glauberman said the airline is honoring coupons sold through its First Hawaiian Bank partnership, but no longer sells coupons at its ticket counters. He said airline officials are studying the coupon program and have not decided its future.

"They haven't made the decision one way or the other," Glauberman said. "It's complicated by the fact that we have a current offer by one of the banks."

Hawaiian travelers looking for the best price will need to book their seats for a specific time a week ahead of their flight or pay a higher price. Coupons for one-way flights go for about $72. If travelers don't book ahead, the cost of an unrestricted ticket is higher ­ running as much as $92.50. Changing existing reservations will cost $15.

Doing away with coupons is the latest development in what is expected to be continuing efforts by the airlines to cut costs and make interisland flights profitable. Hawaiian and Aloha airlines received federal approval in September under an anti-trust exemption that allows them to coordinate capacity on some interisland routes.

Wendy Goodenow, owner of Honolulu travel agency HNL Travel Associates, said local residents are used to coupons and will not like making reservations a week ahead.

"You can't just have a piece of paper in your hand and go to the airport and get on a flight," Goodenow said. "Business people are really the ones that are going to hurt on this. They won't be able to just get up and go."

She said some businesses simply like the convenience of issuing coupons to employees for last-minute business travel while others use coupons to keep from revealing the names of traveling executives.

Goodenow said travel agencies and tour wholesalers that buy coupons and resell them to the public may increase prices on the heels of Hawaiian's announcement.

Hawaiian Airlines spokesman Keoni Wagner said the end of coupons will save the airline money, allowing it to electronically conduct transactions and store information. It will also allow the airline to better manage its inventory of seats on flights since it will know how many people are booked on any given flight.

However, the end of the coupon program alone will not necessarily make the interisland flight market profitable, he said.

"This is certainly a step in the right direction but it's far too early to say for sure," Wagner said.

The coupons are sold through various retailers and wholesalers as well as Bank of Hawaii ATMs, Wagner said. He said he expected coupon sales to continue past Monday through travel agents who bought the coupons before the deadline. Goodenow expects consumers to rush in to buy the remaining coupons.

David Saldana, who lives on Kaua'i and commutes to Honolulu two days a week, said he usually flies on Hawaiian Airlines and has always used coupons. He said he will likely continue to fly Hawaiian, but will miss the coupons, which he said were cheaper and more convenient.

"I'll probably get used to it," Saldana said. Adjusting to the electronic tickets could also take some time, he said. "I'm not very much an electronic person yet."

Kaua'i resident Anne Woodard, who flew to O'ahu with a Hawaiian coupon after a visit home for the holidays, said she has often used coupons for the convenience.

"You can just jump on a plane," Woodard said.

She has never used electronic tickets, and was concerned that she and others may not feel comfortable with the switch from coupons to electronic tickets.

"I was the one that never got into the computer thing," Woodard said. "It would take some getting used to."