Hawaiian Airlines’ passengers may be learning how to beat the system.

The state’s oldest carrier collected $13 million in baggage fees in the third quarter, but that was 8.3 percent less than the year-earlier period, leading some analysts to suggest that passengers could be stuffing more items into their carry-ons.

Airline analyst Bob Mann said passengers nationwide are doing whatever they can to reduce or eliminate what they pay for checked bags.

"It’s a game and people play games," said Mann, president of Port Washington, N.Y.-based R.W. Mann & Co. "Flight attendants will tell you that, too. Flight attendants end up being the arbiter of limited space in the overheads."

There are even mainland companies that sell jackets with multiple pockets — Scottevest features one with 37 pockets — that passengers can put items into so they don’t have to pay a $50 round-trip, checked-bag fee, said Rick Seaney, CEO of FareCompare.com.

"Socks in one pockets, shirts in another," he said.

Passengers know they can often avoid the baggage fee if their bag is checked at the door of the plane instead of the check-in counter.

"If people get through TSA (Transportation Security Administration checkpoint) with a carry-on bag, rarely does any airline charge at the gate because it hurts their on-time statistics, and people have learned this," said Seaney. "So if you’re not in the first third or half of the plane, you’ll likely have to gate-check your baggage, and when you gate-check baggage, they don’t charge a fee."

Baggage fees represented more than half of the $25.6 million that Hawaiian earned in the third quarter, according to recent data from the U.S. Department of Transportation’s Bureau of Transportation Statistics. That brought Hawaiian’s total of revenue from baggage fees through the first three quarters of 2011 to $41.6 million. In 2010 Hawaiian collected $15.1 million in baggage fees in the third quarter and $40.3 million through the first three quarters.

The airline is on pace to top its full-year record of $54 million reached in 2010. Final 2011 numbers are due to be released May 10.

Hawaiian spokesman Keoni Wagner said passengers bringing more items on board is likely only part of the reason for the decline in baggage revenue.

"The major factor is that the long-range aircraft that were used for seasonal service between the West Coast and Hawaii during that quarter the previous year were used for new international routes this past year, and international services are priced differently and don’t have the same fees."

Hawaiian also collected $4.3 million in the third quarter from reservation cancellation and change fees — down 8.5 percent from $4.8 million a year ago — to bring its nine-month total to $13.4 million. In 2010 Hawaiian brought in $18.2 million from reservation cancellation and change fees. Hawaiian charges fees from $25 to $100 for ticket cancellation and from $15 to $449 for ticketing changes or upgrades depending on the destination.

On mainland routes Hawaiian charges $25 for the first checked bag and $35 for the second checked bag. For interisland travel Hawaiian charges $17 for both the first and second checked bags. The airline raised its interisland fee for the first checked bag to $17 from $10 on Sept. 1. There is no charge for the first two checked bags on international flights.

Seaney said since Hawaiian has a 25-pound limit for carry-ons, passengers are going right up to the weight limit.

"There are also credit card programs that waive fees or reimburse folks, so everyone is trying to get around fees," Seaney said. "It’s a bit of a game out there."

Mann said airlines are learning that they can generate more revenue by charging ancillary fees for more services besides baggage.

"If a carrier is smart about it, they price their product at a lower price point, generating more demand, and then sell ancillary services to those passengers who value it," he said.

"So if it’s done properly, in theory it should allow you to maximize revenue more so than with normal revenue management techniques."