Forget about getting bumped up to first class. Delta Airlines is now bumping its best customers off commercial flights entirely -- and onto private jets.

The program got off the ground last week, according to Bloomberg, with its first flight traveling from Cincinnati to Atlanta.

 To be eligible for the upgrade, fliers must have at least 125,000 miles in travel and $15,000 in annual spending with the airline. The bump costs an extra $300 to $800.

In addition to improving the loyalty among some of Delta’s best customers, the program has a side benefit for Delta, allowing it to get some value from positioning flights, known as “empty legs,” which make up about 30 percent of industry flying.

Delta and other airlines have been shifting their loyalty programs in ways that make it easier for elite flyers to earn rewards and more difficult for more irregular customers.

Related: Rethinking airline points strategy with the Points Guy

Starting in June 2016, Delta will issue rewards based on the amount of money spent rather than miles traveled, and the airline may change the number of miles necessary to book a flight based on demand and other factors.

Analysts say that other airlines may follow suit. Airline reward programs have been unsuccessful in fostering loyalty among patrons, many of whom book flights based on cost and convenience rather than brand preference. Only 44 percent of travelers and 40 percent of business travelers fly at least three-quarters of their miles on their preferred airline, reports Deloitte.

Delta’s reward program ranked 9^th on U.S. News’ annual ranking of the best airline rewards programs, released this week, receiving 3.1 stars out of 5. Alaska Airlines was ranked first.