Very few topics generate more frustrated comments from readers than stories on frequent flier miles. They can't find a seat, the seat they want costs too many miles, the program they use has too many restrictions.

Airline consulting firm IdeaWorks just released its ezRez Reward Seat Availability Study. The study looks at the generosity of airline reward programs by trying to book reward seats in March and early April for travel between June and October 2011. The survey looks at 24 airlines, many based out of the country, and tries to net seats at the lowest reward level.

The results? An airline that doesn't fly to the U.S. came out on top with 100 percent success booking reward tickets. That airline is GOL, which flies in Latin America.

Coming in second place is Southwest Airlines' Rapid Rewards program, which came out on top in last year's survey.

Several foreign airlines follow on the list. The next U.S.-based airline is JetBlue, coming in 8th with the ability to book reward tickets 79 percent of the time.

Delta Air Lines' SkyMiles program with 27 percent availability and U.S. Airways, with 26 percent availability, made up the bottom of the pack  - just like last year.

However, both airlines had more available reward tickets this year.

Interestingly, by waiting to search for seats just five to 15 days before travel, seats could be booked using Delta SkyMiles 42.5 percent of the time.

Sun Country was not included in the survey.

Here are the results of the U.S. Carriers:


Rank Airline Program Total Availability 2011 vs. 2010
1 Southwest Rapid Rewards 99.3% No change
2 JetBlue TrueBlue 79.3% New for 2011
3 United Airlines Mileage Plus 71.4% +2.8 pts
4 Continental Airlines OnePass 71.4% No change
5 Alaska Airlines Mileage Plan 64.3% -10.7 pts
6 American Airlines AAdvantage 62.9% +5 pts
7 AirTran Airways A+ Rewards 47.1% -20.8 pts
8 Delta Air Lines SkyMiles 27.1% +14.2 pts
9 US Airways Dividend Miles 25.7% +15 pts