Frequent-flier seats harder to find

Today's travel quiz: Which airline has the worst seat availability for travelers trying to redeem their frequent-flier miles, according to a new survey?

• US Airways was lowest with a 10.7% seat availability rate.
• Delta Airlines' SkyMiles program was next at 12.9%.
• The third worst on the list was the Miles&Smiles program of Turkish Airlines, 35.3%.

Some U.S. airlines were among the best for redeeming frequent-flier miles for trips:

• Rapid Rewards of Southwest Airlines had 99.3% seat availability.
• Air Berlin's Topbonus program, 98.6%.
• Air Canada's Aeroplane program, 93.6%.
• Australian-based Virgin Blue's Velocity program, 90%.
• Second among U.S. airlines was Alaska Airlines, at 75%.
• Continental and United were 71.4% and 68.6%, respectively.

Airline consulting firm IdeaWorks and ezRez Software Inc. conducted the survey (.pdf file) by making 6,160 queries at airline frequent-flier websites in February and March for travel in June through October. Twenty-two airlines were included. The standard redemption rate for miles applied.

The Wall Street Journal's The Middle Seat blog was among the major media sites that examined the results:

The numbers codify what a lot of fliers have suspected for some time, that some airlines are making it almost impossible to score a free trip using miles -- at least without having to pay a significantly higher price in miles than the standard award. The problem is, in part, that there are just too many miles chasing too few seats.

The survey report observes that frequent-flier miles can be an effective tool for building customer loyalty, and that airlines have gotten more creative with benefits. "Frequent flier programs have an abundant choice of methods to reward members for their loyalty," it said. "In addition, pay-with-point options give points an almost cash-like quality. One-way rewards are also becoming more prevalent."

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So many miles, so few planes

However, the WSJ says the number of frequent-flier rewards redeemed dropped between 2008 and last year, even at generous Southwest. Alaska and JetBlue were notable exceptions. So why do some airlines make it tougher to use those miles?

• Worldwide, there are 10 trillion unused frequent-flier miles, the WSJ says, including miles sold to credit card companies and hotels that award them to customers. Last year American Airlines alone issued 175 billion miles.
• There are fewer available seats overall as airlines cut back on flights. "In February, the average commercial plane in the U.S. flew 76.6% full, the highest percentage for that month since World War II, according to the U.S. Department of Transportation," Hugo Martin of the Los Angeles Times reports.
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What should you do with your miles? Scott McCartney at The Middle Seat offers several good suggestions -- using them for seat upgrades, in particular. However, more airlines are now requiring that you also throw some cash into that deal.

Also, if you couldn't score a free ride with frequent-flier miles months in advance of your trip, try again. US Airways, for one, says it tends to release more seats closer to departure dates.

Tell us about your experience. Are you finding it more difficult to fly for free with your miles?

More at MSN Money:

• Find a credit card: Top travel-points cards
• 5 ways for shoppers to track rewards
• Earn miles with your electric bill
• Credit card rewards: 4 new traps