In the year since a Kentucky doctor was violently dragged off a United Airlines flight after refusing to give up his seat, the number of passengers bumped from their flights has dropped significantly and airlines have reduced overbooking. Even so, consumer advocates and the lawyer who represented David Dao said they are disappointed by how little has changed in the wake of the incident that drew worldwide condemnation and calls to boycott the airline.

“We have seen much less improvement than we had hoped for,” said Thomas Demetrio, the Chicago-based lawyer who represented Dao in his case against United. “The airline industry is not closely regulated, and I thought this would change things.”

Added William J. McGee, aviation adviser for Consumers Union: “Any changes that airlines made are, frankly, not very impressive.”

Dao was a passenger aboard a flight from Chicago’s O’Hare International Airport to Louisville on April 9, 2017. Passengers had already boarded the flight when a United representative asked for volunteers to give up their seats. The airline said it needed the seats to make room for crew members who needed to be in Louisville so they could staff another flight the next morning. Two other passengers gave up their seats, but when United officials approached Dao, he declined.

Airline police were summoned and Dao was dragged off the plane. Video taken by other passengers and shared widely on social media showed Dao screaming as he was removed from the aircraft and then again when he suddenly returned to the plane, looking confused, his faced bloodied.

The video fueled outrage in the United States and around the world and there were calls for a boycott. United’s stock price tumbled and chief executive Oscar Munoz’s attempts to tamp down the furor only made the situation worse.

Less than a month after the incident, the airline reached a confidential settlement with Dao.

United officials say they have learned lessons from the incident.

“Flight 3411 was a defining moment for United Airlines and it is our responsibility — our mission — to make sure we as a company and all of our 90,000 employees learn from that experience,” United spokesman Charles Hobart said. “The changes we have implemented better serve our customers while empowering our employees.”

The airline outlined a 10-point plan they say puts customers first. Among the changes: Travelers who voluntarily give up their seats are eligible to receive up to $10,000 in travel certificates. The airline — as well as other carriers — also promised to reexamine its policy of overbooking — selling more seats than are available on a flight. And officials said airline personnel would no longer call outside law enforcement officials to remove passengers from flights unless it was a safety or security matter.

After the United incident, other major airlines made similar pledges. In hearings on Capitol Hill, airline executives said they would stop overbooking flights, and major carriers including American and Delta increased the compensation for passengers who are bumped from their flights.

Lawmakers introduced a flurry of legislation, but in the end, airlines were largely left to police themselves. The Transportation Department, which also investigated Dao’s removal, declined to fine United, saying that although the airline violated some rules regarding the overbooking of flights, investigators found no evidence of race or nationality-based discrimination in the incident. United, they concluded, had not engaged in a pattern of rule-breaking that would warrant a fine.

Still, industry executives say progress has been made. They point to figures from the Bureau of Transportation Statistics that show that the number of passengers bumped from flights in 2017 was the lowest in decades. According to BTS, carriers posted a bumping rate of 0.34 per 10,000 passengers. It was also a decline from 2016 of 0.62 per 10,000 passengers.

The number of passenger complaints however, increased 1.3 percent in 2017, to 18,148, from the previous year’s total of 17,908.

McGee, of Consumers Union, noted that statistics collected by the federal government don’t always provide a complete picture of traveler sentiment. For example, he said the federal statistics don’t include complaints made directly to airlines.

“The good news is that DOT has a database where they will accept complaints,” he said. “The bad news is that very few people realize that.”

Airlines, including United, have continued to come under fire for their treatment of travelers.

In October, the NAACP issued a “travel advisory” urging travelers, particularly African Americans, to rethink whether they should use American Airlines. NAACP officials cited a “troubling pattern of disturbing incidents” in issuing the advisory. American Airlines officials, who met with NAACP representatives, emphasized that they were committed to providing “a positive, safe travel experience for everyone who flies with us.”

Earlier this year, United again found itself back on the defensive after a 1o-month-old puppy suffocated aboard one of its flights. A flight attendant for the flight from Houston to New York allegedly told the pet’s owner, who was traveling with the dog and her two children, that the animal had to be placed in its carrier and placed in an overhead bin. Witnesses said the flight attendant told the woman that if she didn’t comply, the family would not be allowed to travel.  The woman placed the puppy in its carrier in the overhead bin, and when the flight arrived in New York the puppy was no longer breathing. The airline took responsibility and pledged to reexamine its policies regarding animals.

Even so, at a time when record numbers of people are flying, industry executives say they are sensitive to the criticism.

“U.S. airlines remain steadfast in our commitment to improving the customer service experience for travelers and ensuring that they receive the respect and dignity that they deserve,” said Alison McAfee, spokeswoman for Airlines for America, a trade group that represents some of the nation’s largest carriers. “The industry continues to work and invest in our ultimate goal of providing a safe, efficient and enjoyable travel experience each and every day.”

This post has been updated to clarify that the NAACP issued a travel advisory for American Airlines.