Two of the nation’s largest airlines, United and Delta, have adopted major changes to their loyalty reward programs that experts say will benefit the airlines at the expense of passengers. But most reward program members are unaware of the changes, a survey found.

Of the reward club members who are aware of the changes, the new rules may be chasing off more travelers than it attracts, according to an online survey of more than 1,000 reward club members who have flown in the past year.

"They have upset more people than they have pleased with these changes," said Brian Karim­zad, director of the website that sponsored the survey, MileCards.com, which monitors and rates reward programs.

Starting Jan. 1, Delta’s SkyMiles program was overhauled to offer members reward miles based on how much money they spend instead of the number of miles flown. United’s MileagePlus program switched to a similar system March 1.

The changes mean that high-paying fliers in the front of the plane earn more points than passengers in the economy section of the same flight.

But Karimzad’s survey found that 67 percent of United fliers and 69 percent of Delta fliers were unaware of the changes.

"People have some real choices here," he said. "If people sit down and look at what they earn, they might twice think about booking United or Delta on their next flight."

According to the survey, 26 percent of United fliers who knew about the changes said they were less likely to book with the carrier, 11 percent said they were more likely and 63 percent said the changes to the program made no difference.

For Delta fliers, 23 percent said they were less likely to book on the carrier because of the changes, and 16 percent said they were more likely to book, with the balance saying it made no difference, according to the survey.

In response to the survey, Delta said the airline had increased award seat availability and improved the online shopping experience. United said the carrier made a serious effort to notify MileagePlus members about the changes, adding that "these changes provide additional value to our most loyal members."

Hugo Martin, Los Angeles Times