American, United, Continental, and US Airways all boosted fares on flights within the lower 48 states by $10 per round trip. Delta is raising fares too, in the $10-$20 range depending upon the flight length. All this in the face of increased costs for jet fuel. So far, none of the low-cost carriers – AirTran, JetBlue, or Southwest – have raised fares. Yet.

According to the 2011 Customer Loyalty Engagement Index, expectations regarding “Rates & Extra Charges” have gone up again this year. And although flyers don’t expect their flights to be free, when it comes to fares even the budget airlines are only rated fair by their own customers, their value-for-dollar assessments looking like this:

Southwest 77%

JetBlue 75%

Delta 72%

United 69%

Continental 68%

Northwest 68%

US Airways 67%

American 65%

Business is business, after all, but it’s the 6th time this year carriers have raised rates. The recent hike follows an industry profit of more than $15 billion last year, but in fairness, the industry had lost $10 billion in 2009, and $16 billion the year before that.

In response to passenger complaints, airlines are rationalizing the increased fares by pointing out that they are only associated with how long a trip you’re taking. Of course, you might follow the advice offered by George Carlin: “Kilometers are shorter than miles. Save money and book your trip in kilometers.”