Is it getting even harder to find a free ticket?

Cashing in frequent-flier miles — or, at least, trying to — has long been a sore subject for business travelers, who complain that free seats are never available when they want them. And newly announced cuts in capacity by several major carriers, including Delta, American and United, could make the problem worse.

Last week Continental Airlines (CAL) said it would reduce about 11% of large-jet capacity in September, and other airlines — Delta, (DAL) American (AMR) and United (UAUA) — have announced double-digit capacity cuts for fall.

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"I think a pullback of capacity will reduce the number of seats allotted for reward travel," says Jay Sorensen, president of IdeaWorks, a Wisconsin consulting company that regularly conducts airline and travel industry marketing studies.

United Airlines spokeswoman Robin Urbanski says fewer flights will mean fewer free seats overall for frequent fliers, but each flight will have the same number of free seats as in the past.

American Airlines spokesman Tim Wagner says "too many factors" are involved — such as customer demand and amount of seats filled for each flight — to determine now whether the number of free seats will be affected.

Many frequent fliers are skeptical.

"With cutbacks, just pure mathematics tells you that there has to be less seats," says Scott Zebedis, of Denver, who works for a non-profit foundation and flew more than 100,000 miles on United last year.

The route and flight cuts could change the conclusions drawn from a recent study that said that carriers have been "unfairly criticized" about the availability of free seats in frequent-flier programs.

The IdeaWorks study, done in April and May, shows that "a reasonable supply" of free seats is available to frequent-flier members.

Sorensen says that could change after the fall cutbacks because, "When an airline is faced with the decision of giving a seat as a reward vs. selling it to a customer, the choice has traditionally been to sell it."

For its frequent-flier study, IdeaWorks made 5,210 queries in April and May for free seats to eight airlines' websites. Three-quarters of the queries were for at least two seats on round-trip flights to U.S. destinations this summer, or Sept. 4, 2008, through Jan. 26, 2009, excluding holiday periods. A quarter of the queries were for seats for a family of four for summer flights.

IdeaWorks inquired about free seats for the minimum amount of miles or credits required in each program and selected, based on federal government data, the most popular destinations for award travel on each airline.

Free seats are easiest to book on American and Southwest, (LUV) according to the IdeaWorks study. It also concluded that it's difficult for a family to obtain free seats from most carriers a few months before a summer vacation.

Free seats to Hawaii and other vacation destinations affected by the cutbacks could get tighter, but the cutbacks may have less impact on busy routes between major cities — the most popular awards. The most popular free flights last year, for example, were New York-Los Angeles on American and Atlanta-New York on Delta, Sorensen says.

Despite IdeaWorks' findings, some frequent fliers are not convinced that airlines are making a sufficient amount of free seats available.

Lori Strumpf, president of a management consulting company in Washington, says it's gotten "more difficult" to book free seats during the past 12 months.

"They're never available in what I consider a reasonable amount of lead time — two or three months," she says. "You have to book almost a year in advance. Who does that? And it takes forever to go through the process on the phone."

But that's not the experience of some other frequent fliers, including Mark Von Grey of St. Paul.

"I have found it pretty easy to book seats," says the sales representative in the utility industry. "There seems to be more availability with less blocked days."

Von Grey and other frequent fliers, however, say free seats often are unavailable for 25,000 miles — most airlines' minimum award level. "On one specific trip, it cost 25,000 miles to go, and 75,000 to return," Von Grey says. "Domestic travel should not be so costly."

The IdeaWorks study did not take into account the quality of the flights on which free seats are offered. Many frequent fliers complain that many of the free seats available are on less desirable multi-stop, late-night or very early morning flights.

Alaska Airlines (ALK) spokeswoman Marianne Lindsey says, "It is generally easier to find award seats and sale fares on off-peak flights." It is also difficult for a family of four to find free seats a few months before a summer vacation. For six of eight airlines queried, IdeaWorks succeeded on fewer than half of its attempts to book four free seats for travel this summer.

"All flights have award seats," United's Urbanski says, "and during the summer travel season, these seats are among the first to go."

Wagner says most members of American's frequent-flier program book their vacation flights far in advance and "scoop up most of the award seats." He says it's "astounding" that IdeaWorks succeeded on 45% of its attempts to book four American seats so near to the peak summer travel season.

It may be wise for families not to count on free seats for their vacations, Sorensen says. He suggests that families replace the credit cards they use to earn frequent-flier miles with cards that earn free hotel stays. "For a family of five like mine, it's probably not best to rely on free seats from a frequent-flier program," he says. "It may be best to find one free seat and to pay for the rest of them."

With the impending flight cutbacks, Sorensen advises fliers to book their free seats as far in advance as possible. He also says there may be more free seat availability at major hub airports, so fliers who live in Milwaukee, for example, may instead opt to fly out of Chicago.

Fliers who rely on free seats for family vacations may need to be more flexible in choosing a destination, Sorensen says. "You may think you have to go to Orlando, but you might have a just as enjoyable experience if you go to Miami and take the family to the Everglades."