Delta Air Lines, making a bigger play for business travellers, said it would change its frequent-flyer program to base miles earned toward free flights on how much customers spend rather than the distance travelled.
The move, which will take effect next year, will benefit corporate travellers who are the most profitable for airlines.
Those travellers can spend two to three times or more than leisure passengers, who tend to look for bargains.
Business travellers also tend to book more flights.
Delta's change will sweeten mileage awards for travellers who pay more for airline tickets.
George Hamlin, an aviation consultant in Fairfax, Virginia, said the frequent-flyer plan change comes as airlines look to cater more to most profitable customers.
"It's going to upset a lot of people but it's economic reality," Hamlin said.
"Leisure passengers typically seek out price, and carrier loyalty is often a second priority."
As of January 1 of next year, Delta passengers will garner between 5 and 11 miles for each dollar spent on airfares depending on their frequent-flyer status, with those at the highest level earning the most, the carrier said.
Purchases with a Delta SkyMiles credit card will earn additional miles. Delta is part of the SkyTeam alliance, whose members include Air France, China Southern, China Eastern, Vietnam Airlines and KLM.
Airline loyalty programs can help increase business among business travellers who fly often.
Miles accrued under Delta's loyalty program do not expire.
Brian Kelly, founder of ThePointsGuy.com, a travel website that focuses on frequent-flyer issues, said the move could be good for travellers who spend a lot on tickets but don't fly longer distances.
"It hurts consumers who are savvy with their money and go for the most reasonable fares," said Kelly.
JetBlue Airways and Southwest Airlines also tie frequent-flyer miles earned to the amount spent on a ticket, and Hamlin said he expects other major US airlines to follow suit.
Delta has taken many moves to draw more business travellers in recent years.
It renovated terminals at LaGuardia and John F Kennedy International airports in New York, a market rich with business customers.
It is looking to lure more corporate passengers with a joint venture it began this year with Britain's Virgin Atlantic Airways, a partnership that strengthened Delta's presence at London's Heathrow airport.
Robert Mann, an aviation consultant in Port Washington, New York, said Delta's move made sense and is now technologically feasible since airlines can track travellers' spending.
"The spend, the fares paid and the willingness to buy up are the best approximations of a customer's contribution to carrier profitability, and that's what you want to reward," Mann said.
"That's what loyalty is."
American Airlines and United Continental declined to comment on Delta's move or any possible changes to their programs.