United Airlines has made a change to its program for children flying alone, expanding the age range of kids who use a $150 service when flying without an accompanying adult.

Now, children ages five to 15 who are traveling without a parent or legal guardian will need to pay an extra fee for “unaccompanied minor service,” which ensures staff members chaperone children to their seats and meet their waiting adults upon landing, according to the airline. The previous upper limit of the age range was 12 years old.

The change puts United ual in line with two other major airlines, Delta dal and American Airlines aal . Both charge a mandatory $150 fee for children ages five to 14 who are traveling alone.

The new policy has earned the ire of some industry experts who would prefer the carrier upgraded the service instead of widening the age range. “Obviously, they are going to generate more revenue from this,”Jay Sorenson, a consultant on airline revenue and president of IdeaWorksCo, told The Los Angeles Times. “They should make an attempt to improve the product.”

Sorenson cited the move made by Air New Zealand to introduce the “Airband,” a wrist band that the airline will give to children traveling alone that is embedded with a chip that sends text notifications to the kid’s contacts.

United told The Los Angeles Times that the change was made after some deliberation. “We made a thoughtful review of the policy and decided that this change will provide the best possible care for these travelers,” United spokesman Charles Hobart said.

Fortune has reached out to United Airlines for comment.