Southwest Airlines gives most free seats to fliers, according to survey

Frequent fliers are often flying blind when it comes to knowing which airline consistently offers free seats in exchange for their hard-earned miles.

Even though around 100 million Americans participate in one or more airline loyalty programs, carriers are not required to divulge how often they provide seats to frequent fliers -- leaving little ability for consumers to gauge these programs' worth.

"I think there's much too little transparency in this area," said Tim Winship, editor-at-large for smartertravel.com. "Consumers do their part in adding to the financial well-being of these airlines without having any idea whatsoever about how their airline does when it comes to the promise of redeeming a free seat with their miles."

Well, that's about to change. A new study by IdeaWorks and ezRez Software seeks to quantify for the first time all that anecdotal information flying around about which frequent flier programs are the most effective.