The solution? Keep the basic ticket price relatively low and charge fliers heavily for checking bags.
 
According to report released by the Bureau of Transport Statistics, U.S. airlines added more than $1.7 billion in baggage fees to their coffers, the most ever received in the first six months of a year.

In the first quarter of 2012, America's 15 largest airlines collected $816 million. The number grew to $932 million in the second quarter.
 
Leading the way is Delta Air Lines (DAL), with $231 million in the second quarter, while United Airlines (UAL) was second with $195 million. American, US Airways (LCC) and Southwest (LUV) rounded out the top five. (Southwest does not charge for the first checked bag, but its subsidiary AirTran Airways does.)
 
Baggage fees were introduced in 2008 and have gone up since, as as Scott Mayerowitz of AP points out:
 

Many of these fees were first introduced to allow airlines to offset rising fuel costs. In 2007, the airlines paid an average of $2.09 a gallon for jet fuel. The next year, prices spiked 46% to $3.06. During the first seven months of this year, airlines have paid an average of $2.96 a gallon.
 
Airfares have climbed in recent years but not as fast as the cost of fuel. Passengers have shown reluctance to book tickets if the base fare is too high, hence the introduction of the fees.

 
The increase in baggage fees is also a part of the overarching story of how airlines have been increasingly dependent on ancillary revenue since the industry was deregulated in the 1970s.
 
When low-cost competitors such as Southwest, Spirit Airlines (SAVE) and JetBlue (JBLU) entered the market, offering low airfares by cutting perks, legacy carriers like Delta and United had to go in the same direction as well.
 
In the past, the cost of meals, checked baggage and the use of reservation agents were built into air tickets, which were priced higher. Customers who didn't check baggage in were in effect subsidizing those who did.
 
These days, you pay a low price for your ticket and decide whether or not you want to forgo the frills (although some people would argue the first checked bag isn't a frill).
 
Airlines have become increasingly dependent on ancillary revenue like baggage fees and reservation-change fees. In 2005, ancillary revenue represented 7.1% of United's total revenue. In 2010, that rose to 9.3%. Delta experienced a rise from 8.3% to 13.0% in the same time frame.
 
While passengers may have the choice of deciding whether to pay and check in baggage, they increasing do not have choices in other areas of air travel. In the same report, the BTS notes that as US airlines continue to consolidate in a tumultuous industry, passengers "can expect fewer carriers to choose from (and) fewer flights to smaller cities."

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