When weather forecasters predicted severe winter storms across the country in the last few weeks, airlines sent their customers a steady stream of e-mail and text messages, giving them a chance to change their itineraries ahead of the bad weather. Those who took advantage of the waivers had what has become a rare consolation in air travel: They received a service from the airlines without paying for it. In the space of 18 months, the concept of a plane ticket has been transformed from an all-inclusive purchase to a pay-as-you-go plan, turning the relationship between airlines and customers increasingly sour. Every time a passenger books a ticket, it seems, major airlines have come up with more ways to charge for what once was free, like fees for reserving more desirable seats in the economy section of the plane. David Stewart, a commodities trader in New York, was stunned to learn last week that he would have to pay $80 for an aisle seat he wanted on a Virgin Atlantic flight to London. Stewart, who is 6 foot 5, says he managed to cajole a gate agent into seating him there anyway. But ahead of and behind him, an entire section of aisle seats sat empty, apparently because other passengers declined to pay for them. 'It's bad customer service,' says Stewart. 'It would be in their interests to do this better.' A Virgin spokeswoman called the fee 'common practice within the industry.' Adding to travelers' frustration is that the long-cited reason for the switch to 'a la carte' pricing -- record oil prices -- is no longer the driving force behind the changes. Instead, airlines now cite their inability to make money, and consumers' resistance to higher ticket prices, as their reason for thinking up new ways to make customers pay extra. Over the last decade, they lost $55 billion, according to the International Air Transport Association, the airlines' global trade group. And the outlook for 2010 remains glum. 'We need to return to profitability, and we need to do so immediately,' says Mark Bergsrud, the senior vice president for marketing at Continental Airlines, echoing what has become an industry mantra. He and some other airline executives offer another line of reasoning for the new environment: the me-too factor. Cell-phone providers, sports arenas and theaters all add charges on top of the basic price of what they sell. Customers are used to it, so why shouldn't the airlines join in? 'It's something that's happening throughout business,' Bergsrud says, 'and we're just slower getting there than many others.' Consumer advocates say the tactic will ultimately backfire. 'I frankly think the airlines are going to find out that these unbundling gimmicks do not work,' says Paul Hudson, a lawyer and the executive director of the Aviation Consumer Action Project. 'People will reach a point and say, 'That's it.'' There is disagreement about the practice, even in the industry. Robin Hayes, an executive vice president and chief commercial officer at JetBlue Airways, acknowledges that customers find the charges very annoying. 'On the whole, for the last 10 years, the industry has done a really rotten job of looking after passengers,' he says. While many customers have accepted the changes, that's because 'there's very little choice,' Hayes says. 'But the industry would be foolish' to keep adding new charges for things passengers had become accustomed to receiving in the ticket price. JetBlue has added some fees, but not to check the first bag and it still serves some complimentary snacks. Bergsrud, however, sees the airline industry becoming much more like the hotel industry, which has long charged different room rates based on location and amenities. 'It's like hotels with an ocean, a garden and a parking-lot view,' Bergsrud says. He theorizes that passengers having the toughest time accepting the changes are those who fly only a few times a year, while business travelers and those often on the road take the new atmosphere in stride -- in part because they earn enough miles to be exempt from many charges. Graham Howe, a banker in London who flies often, disagrees. 'It's taking advantage of the customer,' he says. 'It all adds up.' Airlines say they are not unsympathetic. Daniel P. Garton, the executive vice president for marketing at American Airlines, says its surveys have reflected passengers' discomfort as the airlines take apart their tickets and recalculate what they want to include in the basic price. But the surveys show that more than half of customers understand why American has had to charge for things they used to expect free, a response Garton finds encouraging. 'We're still going through the hardest part of it, because we are unbundling what for the better part of 70 years has been a fixed-price menu,' Garton says. 'You have to get through this phase so people can get used to it.' Major airlines have been cutting back on frills for more than two decades, ever since American began reducing the number of olives it served in each salad. Hot meals were among the first to go on short flights, sacrificed in a wave of cuts after the September 2001 attacks. But lately, the pace of change has been faster, and made travel more complex, uncomfortable and aggravating. 'It's horrible,' says Matthew B. Stern, a professor of neurology at the University of Pennsylvania who can't avoid air travel because he lectures and consults around the world. But after his golf clubs were lost on a trip he took with his son, he refuses to check luggage. On longer trips, he sends bags ahead by courier, and for short trips he generally gets by with just one carry-on bag. 'Traveling by plane nowadays is like low-class bus travel in the 1950s,' he says. But back then, bus lines didn't charge to take a suitcase, or to select a specific seat. And analysts say the airlines have bungled the switch from all-inclusive to a la carte, irritating already cranky fliers even more. 'How do you run an industry where people hate you?' says Robert W. Mann, an airline analyst based in Port Washington, N.Y. 'What they don't realize is the long-term implications of the things that they are doing.' Mann says he believes that the dizzying array of new charges, coupled with security uncertainties and the weak economy, is deterring discretionary travelers -- those who once thought nothing of jumping on a plane for a weekend trip. Airlines need those passengers to fill seats left vacant after so many companies cut back on business travel. They include Sanjay Lad, a dentist who lives in Los Angeles. In the past, he says, he regularly took last-minute flights to nearby cities like Las Vegas for a few days of relaxation. But now he might drive to avoid paying fees, like the $50 he paid last month to check his skis on a round-trip Delta flight to Salt Lake City. 'A lot of us understand the crisis the industry is in,' says Lad, 'but I'd consider whether it's financially feasible before I just jump on a plane.' Still, passengers cannot escape some responsibility for the airlines' tactics, says Tim Winship, editor of SmarterTravel.com. 'We have to look at ourselves in the mirror as consumers, and acknowledge the extent to which our own price sensitivity has contributed to the way things are,' he says. That sensitivity has been made clear during the recession. After raising fares 15 times in 2008 to offset record fuel costs, the airlines were able to raise prices only four times in 2009, when the slow economy caused air travel to drop by about 25 percent. From July to September, the most recent quarter for which information is available, the average round-trip domestic fare was $306, down from $358 in the period a year earlier, according to the government's Bureau of Transportation Statistics. So far this year, airlines have twice tried unsuccessfully to raise average prices. The first was an attempted $16 round-trip increase in January by American, Continental, Delta and United, and a $10 round-trip increase that many carriers tried this month. But low-fare airlines resisted, and prices stayed higher for only a few days before the airlines retreated. 'They're testing the price elasticity of consumers, and consumers are saying, 'We're very sensitive to price,'' says Rick Seaney, chief executive of FareCompare.com, which tracks airfares. 'Consumers are just expecting weekly discounts. One dollar matters nowadays.' By contrast, the airlines have had a much easier time adding and increasing fees. The price to check a bag rose 50 percent during the last year, when they collectively took in $3.8 million in baggage and other fees. It now costs an average of $25 to check a first bag on many major airlines, though discounts are available if booked ahead online. The airlines have also added surcharges to travel during the most popular times, like the week between Christmas and New Year's. But the fees are a fraction of what the carriers could collect if they could charge more for tickets. 'Not everybody eats. Not everybody drinks. Not everybody checks a bag,' says Bergsrud. Though he did not want to pay extra for his seat, Stewart, the commodities trader, says he'd rather see airlines charge for options like a pillow or a blanket than raise ticket prices so that every passenger could receive one. 'It's better to charge the 10 people who want them,' he says. Still, there is some evidence that fewer fees help attract passengers. Southwest Airlines, the largest low-fare airline in the United States, gained a point of market share in 2009 and attributed the increase to its decision not to charge for checking a first or second bag. Its chief executive, Gary C. Kelly, says his competitors are damaging their relationship with customers by rolling out so many changes so quickly. 'They view customers as just numbers on a list, as opposed to thinking about how they can best meet their needs,' says Kelly. 'It's kind of silly to say, 'We want to win more passengers' but not let them take a bag when they travel.' Kelly, whose airline earned money in 2009, a year when the rest of the industry collectively lost about $5 billion, agrees that many carriers will not survive if they are not profitable. 'That's a given,' he says. 'But you can decide whether to take care of people and treat customers like guests in your home.' Hayes at JetBlue agrees that attitude has to be fundamental. 'You have to build a culture around wanting to serve customers,' he says. But neither airline has escaped criticism this past year. Southwest, which for a time embraced 'Freedom From Fees' as its advertising slogan, dropped that in favor of 'Bags Fly Free' after it began charging for extras like securing a place in the first boarding group, which costs $10. JetBlue has also upset some passengers, including Mann, the analyst, for charging to change a reservation and to select seats with extra legroom. But the fees allow customers to 'choose what they want,' says Hayes. Amid the anger about taking apart a plane ticket, analysts are beginning to wonder if airlines might be better off 'rebundling' their tickets, although that isn't likely to happen soon. Until the airlines change their minds, analysts and passengers say openness by the airlines could offset some of travelers' irritation. Beverley Cochran, a nurse from London who works in New York, says she understands the airlines' predicament. 'They have to figure out how to make money,' Cochran says. 'I'm a realist. I know they have to do this, or put the prices up. As long as it's not underhanded, I'm OK with it.' But she, and Lad from Los Angeles, put limits on what they are willing to accept. For Cochran, it would be paying for water or pretzels. To Lad, the line is drawn at charging for carry-on bags. 'For a lot of people, that would be a deal breaker,' he says. 