New York ? Finished with a weeklong business trip earlier than expected, Brent Baer approached the US Airways ticket agent with a smile, eager to catch the 2 p.m. flight to Washington and get home before dark.

But Baer walked away with a dilemma that caused him to grimace: either pay $246 to change the itinerary on a roundtrip ticket that originally cost $98, or save his money and wait 5 1/2 hours for the flight he had originally booked.

With airlines expected to lose nearly $8 billion for the second year in a row, the industry has become less generous with customers like Baer who want to fly on the cheap. By linking hefty fees with tight restrictions, the struggling airlines hope to generate tens of millions of dollars per year in extra revenue.

In short, penny-pinching passengers may have finally met their match: penniless carriers.

“The industry is losing its shirt, is flat on its back and is looking for every dollar of revenue that it can find,” said David Swierenga, chief economist at the Washington-based Air Transport Assn., an industry group.

Carriers have increased fees for paper tickets and extra baggage, taken away senior discounts and increased the cost of travel for children flying unaccompanied by an adult. Hot meals are gone on many domestic flights and alcoholic drinks no longer come free on international ones.

There has even been speculation that carriers could one day offer one rate for passengers who want a meal and another for those who do not.

The airlines have gotten particularly tough with corporate customers, refusing to let them use discounts negotiated by their employer when they purchase cheaper fares aimed at leisure travelers. The cheapest leisure fares are about one-sixth the price of typical business fares.

“The problem for us is that only about one in a dozen passengers is flying at full coach fares,” Don Carty, the chief executive of American Airlines, told Wall Street analysts last week. That’s significant, Carty said, because nearly half of American’s sales come from traditionally higher-paying business travelers.

The latest change by American, US Airways and others the one that wiped a grin off Baer’s face the other day at La Guardia Airport in New York was to put heavy restrictions on nonrefundable tickets, making these inexpensive fares less attractive to travelers who require more flexibility.

The airlines’ message to budget-minded travelers is simple: We can be cheap, too.

Brent Baer, regional manager for a Charlottesville, Va.-based advertising agency, ran into trouble when he recently tried to change his US Airways flight out of La Guardia Airport in New York. With airlines expected to lose some billion for the second year in a row, the industry has become less generous with customers who want to fly on the cheap.

Air travelers began to curtail spending roughly 18 months ago as a result of the economic downturn. The trend was accelerated by last year’s terrorist attacks and, subsequently, the industry relied on dramatic price cuts to lure people back to the skies. The average domestic fare in August was at a 14-year low, according to Swierenga.

The rising popularity of Internet-based travel agents such as Expedia, Orbitz and Travelocity, and the increased market share of low-fare carriers such as AirTran, JetBlue and Southwest, provide further evidence of traveler frugality.

To survive, major carriers undertook a wide range of cost-cutting measures. Employees were laid off. Planes were grounded. Schedules were shrunk. And travel agents’ commissions, which had been reduced, were eliminated. But those changes had little impact on the travel experience.

Changes could hurt sales

By contrast, the stricter rules, extra fees and scaled-back services could aggravate travelers, analysts said.

“I don’t think of the airlines as the bad guys as much as I do the dumb guys,” said Ed Perkins, an advocate for fliers who founded the Consumer Reports Travel Letter. Perkins believes the nickel-and-diming of passengers might not really be worth it for an industry that desperately needs to stimulate demand.

“It reminds me of a corporation that’s losing zillions of dollars and decides to fight back by controlling the way employees use paper clips and scotch tape,” he said.

Under the new rules affecting nonrefundable tickets, customers on most major airlines will have to pay a fee to fly standby and those who miss their flights will have to buy brand new tickets.

Baer, who works for a Charlottesville, Va.-based advertising agency, was unfamiliar with the new rules and was stunned to find out that catching the earlier flight would more than triple his cost. So he called the US Airways reservations department to “moan a little bit” and the carrier eventually allowed him to board the 2 p.m. flight for a reduced fee of $100.

But that still doubled Baer’s air travel expense. In the future, he said, “the question becomes do I buy the refundable fare?”

It is an issue nationwide.

Travelers need to weigh decisions

Pete Buchheit, director of travel at Black & Decker Corp., said employees at the Towson, Md.-based company still will be encouraged to fly on nonrefundables, which make up 77 percent of all tickets purchased by the tool maker. But if employees are not careful about making their flights and sticking to their original travel itineraries, Buchheit estimated the new restrictions and fees could cost the company $1 million during the next year.

“If the attempt was to fence (business travelers) out, I think it’s only going to be semi-successful,” said Kevin Iwamoto, who manages air travel at Hewlett Packard.

While travelers said the new fees and restrictions are an annoyance, they said the benefits of cheap tickets generally outweigh the downside. Still, some said they would be willing to pay a touch more if the industry eased up on the restrictions and fixed the problems that cause delays, including the new security-related hassles.

“I’m almost of a mind to say let them start charging more,” said John Prisco, the chief executive of ELink Communications, a Bethesda, Md.-based high-speed Internet provider. “That way they can add some services back and make flying more enjoyable.”