Airline fees for everything ranging from booking a trip by phone to checking a bag are on the rise, and four carriers are levying fees of $400 or more, a USA TODAY survey of a dozen U.S. airlines shows.
Delta Air Lines charges $400 to change a ticket on some international flights — a $150 increase over its most-expensive flight-change fee in 2011, when USA TODAY did a similar survey.
American Airlines charges $450 for an overweight checked bag weighing 71 to 100 pounds for some international flights, while such a bag on United Airlines' international flights and Hawaiian Airlines' Asian flights costs $400.
Fees are a major source of revenue for the industry. According to the Department of Transportation's Bureau of Transportation Statistics, 15 U.S. airlines reported revenues of $2.6 billion from baggage fees and $2.1 billion from reservation-change fees during the first three quarters last year.
(Read more: Snow snarls post-Super Bowl travelers)
Charging passengers fees "for services they value and are willing to pay for" has "enabled airlines to provide consumers the ultimate choice and control over what they purchase," says Victoria Day, a spokeswoman for the Airlines for America trade group.
Without charging fees last year, airlines would have lost money and offered fewer flights, she says.