Delta Air Lines announces major change to SkyMiles program

Upgrades and free flights may cost more Sky Miles next year. (Delta Air Lines)

Getting a free flight or better seat on Delta Air Lines will cost program members more Sky Miles starting next year.

Last week, the carrier announced a major change to its frequent flier program, becoming the first of the big three U.S. carriers to adopt a “supply and demand” program over its current fixed miles system for upgrades and free flights, reports Skift. This means more popular routes may require more mileage points than shorter flights along less traveled flights.

JetBlue, Southwest and Virgin America already operate under a supply and demand award program.

"The number of miles needed (for a free flight) will change based on destination, demand and other considerations,” according to Delta, who confirmed that the changes will go into effect June 1, 2016.

Anthony Black, a spokesman for Delta, told NBC that “most award prices will stay the same, with a greater availability of awards at the lowest prices and new 7,500 and 10,000 mile one-way awards. Members can take advantage of lower prices immediately, while other price changes won't take affect for travel more than 10 months from now."

Included in the changes is a new “upgrade with miles” option that will be available for customers only at the time of booking travel.

Travel experts have already expressed concern that Delta’s lack of transparency when determining award flight value may hurt consumers in the long term.

"They [Delta] say some prices will be going up and others will stay the same, and this is based on a variety of factors," Gary Leff of the View from the Wing blog told NBC. "(But) they will not share which prices for what trips will go up, and which ones will stay the same, or how consumers will even know what to expect."

Delta says that no airline today tells you exactly when fares will change or increase in price and that they are giving Sky Miles members plenty of notices to prepare.

Black reiterated to NBC, “The award price for some trips will change based on a variety of factors; just like they do today for revenue tickets."