Terry Buchen gets to board his Delta flights early because he has elite status. In theory, he's assured a spot in an overhead bin for his carry-on bag.

In practice, even he has to compete for the coveted space.

Since airlines began charging passengers in 2008 to check their luggage, carry-on bags have multiplied in size and number. That's turned the boarding process into a free-for-all even for business travelers who've traditionally had high enough status to avoid such hassles.

"When a passenger moves my luggage with wheels or handle facing out, if the bin is too small, the bin door will not close," says the golf course agronomist from Williamsburg, Va. "I am very vocal to a passenger when they try and move my bag so theirs will fit because if I allowed it to occur the flight attendant could take my bag and check it."

Soon, Buchen's bag may have a better chance of staying in an overhead bin. Airlines and airplane manufacturers are realizing that overhead bins on most planes aren't big enough to accommodate today's typical carry-on bag. United, Delta, American and US Airways are either retrofitting older planes with bins that can hold roll-aboard bags or purchasing aircraft with bigger bins.

Creating More Cabin Space

Boeing's new 787 Dreamliner and 737s are being built with pivot bins that can better fit standard 9-by-14-by-22-inch roll-aboard bags. New bins also have curved doors that can fit roll-aboard bags wheels first.

"It's part of the philosophy of creating more space in the cabin," says Kent Craver, regional director of passenger satisfaction and revenue at Boeing. "The pivot bin is designed around the shape of standard bags."

Baggage fees have become a major revenue generator for U.S. airlines. From 2008 to 2009, revenue from baggage fees more than doubled.

But last year, for the first time since they began collecting the fees, the nation's 17 largest airlines made less from them than they did the year before, a sign travelers are changing their packing behavior. Baggage fees generated US$3.36 billion in 2011 vs. US$3.4 billion in 2010, the Transportation Department reported last week.

Robert Mann, an airline analyst at R.W. Mann & Co., says many factors could have contributed to the decline, including people packing lighter, carrying on as opposed to checking , or "learning how to 'play the game' and bet on being relieved of bags that won't fit on board on the jet bridge, thereby avoiding fees."

Many passengers and flight attendants say the baggage overload frays nerves and delays take-offs when they have to transfer bags to the belly of the plane.

"Way too many people are carrying on. This slows down the boarding process considerably, especially when you consider most passengers do not listen to instructions at all," says Steve Ording, a national food sales manager in Columbus.

Abby Lunardini, a spokeswoman for Virgin America, estimates that 80% of Virgin's customers board with a personal item, such as a purse, and a carry-on bag, which is what airlines typically allow. United Airlines has done research that shows more travelers aren't necessarily carrying bags aboard. But they're carrying up to the size limit, when they'd taken smaller bags in the past.

Charging for Carry-Ons

Some airlines have tried to discourage carry-ons. Spirit Airlines, the first to charge for carry-ons, will increase the fee to as much as US$100 a bag in November. Allegiant Airlines recently joined Spirit, charging US$35 per carry-on.

Major airlines haven't followed suit. And they're willing to adopt bigger overhead bins even if it could encourage travelers to carry on bags rather than pay to check them.

They say a better boarding process will result in happier travelers, in particular those who travel for business. Business travelers, airlines' most lucrative customers, typically don't pay bag fees because their loyalty program status or use of airline credit cards come with waived fees.

"A customer who has a smooth boarding experience is more likely to report an enjoyable travel experience," says Rahsaan Johnson, a spokesman for United Airlines. And that can mean return customers.

Not everyone believes larger bins are the solution to the rush to stow bags in the cabin. "Carry-on bags slow down the process," frequent traveler Ording says. "I would prefer they save the money making bins bigger and eliminate the check-bag fees so more casual passengers will start checking bags again."

What Airlines Are Doing

Several airlines are taking steps to increase the size of overhead bins so fliers can stow bags in passenger cabins. Among them:

•United Airlines is retrofitting its 152 Airbus aircraft with curved bins that can accommodate up to two-thirds more bags.

•American Airlines' new Boeing 737-800 aircraft can carry 48 more bags in the bins than the MD80 planes they are replacing, spokesman Tim Smith says. The carrier already has 173 of the new planes in its fleet, with 133 more on order. Since 2010, American has also been replacing overhead bins on 76 of its older 737-800s. Other new aircraft with larger bins are on order.

•Delta Air Lines is adding larger bins to its fleet of 58 Boeing 767-300 aircraft. The aircraft will be able to hold 26 more standard-size roller bags than before. Next year, the carrier also will introduce the first of its Boeing 737-900 aircraft, which have bigger bins.

•US Airways expanded bins on its 24-strong Boeing 757 fleet in 2008 to fit bags in lengthwise. Its 24 new Airbus A321s, many of which have already been introduced, have larger bins that fit roll-aboards in wheels first. US Airways has also installed two additional bins on its Airbus A330s. They're the same size as existing bins but add space for more bags, says spokesman Todd Lehmacher.