WASHINGTON — Travelers who use wheelchairs have long complained that airlines frequently damage or lose them.

Now the Biden Administration is trying to change that by proposing new standards for how airlines must accommodate passengers with disabilities.

"Transportation is still inaccessible for far too many people, and that's certainly true for aviation," Transportation Secretary Pete Buttigieg said in a call with reporters. "This is about making sure that all Americans can travel safely and with dignity."

The proposed rule, announced Thursday, would make mishandling of wheelchairs an automatic violation of the Air Carrier Access Act — making it easier to hold airlines accountable when they damage or delay the return of a wheelchair, Buttigieg said.

The rule would mandate that airlines provide more training for employees and contractors who physically assist passengers with disabilities and handle passengers' wheelchairs and other mobility devices. In addition, it would require airlines to provide prompt assistance to passengers with disabilities when boarding and deplaning.

The immediate reaction from disability advocates was largely positive, though some expressed disappointment about what the proposed rule leaves out.

Flying is "by far the part of traveling that I dread the most," said Cory Lee, who writes a blog about accessible travel called Curb Free With Cory Lee. Lee says his powered wheelchair weighs about 400 pounds, and estimates that it's damaged in some way roughly half the time he flies.

"My wheelchair is my legs. And so without it, I'm completely immobile. I can't go anywhere. I can't live my life. I can't do my work or anything," Lee said in an interview. "Air travel is what needs the most help in the travel industry to become more inclusive and accessible. And any step toward getting better is important."

But Lee and other wheelchair users had been hoping for more.

"The rule certainly is doing something, but I don't know if it's doing enough," said Emily Ladau, a disability rights activist and author of the book Demystifying Disability.

Ladau says she wants to see more clarity about what kind of training airline employees will receive, and about how the rule defines "prompt assistance."

"I can't tell you how many times I have sat on the plane waiting for sometimes close to an hour, if not more, just to have my wheelchair returned to me," Ladau said. "And occasionally have found that my wheelchair was not returned to me promptly because it was damaged."

The proposed rule does not include what Lee called his "ultimate dream" to stay in his own wheelchair on a plane. That may still be a long way off, Lee acknowledged.

"I'm really just thrilled that airlines are finally being held accountable to some degree," he said.