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.
To determine which airlines make it easiest to turn reward points into airline seats, IdeaWorks, a Shorewood, Wis., airline consulting firm, and EzRez Software Inc., a San Francisco-based travel supplier, made more than 6,000 booking queries on the websites for 22 frequent flier programs during February and March.
Read more here: Rewards tougher to redeem as airlines fill flights