In a written explanation to the Senate Commerce, Science and Transportation Committee on Wednesday, United Airlines reiterated that it is reviewing its policies following the April 9 incident in which a passenger was dragged off its Chicago-Louisville flight due to “overbooking.”

United CEO Oscar Munoz explained to the committee that the company is reviewing its policies to make sure not to put its passengers, employees and partners in “impossible situations.” The airline has also vowed not “to ask law enforcement officers to remove passengers from our flights unless it is a matter of safety or security.”

“We are working to regain our customers’ trust with the highest quality of service and deepest level of respect and care,” Munoz’s statement read. “As part of my commitment to ensuring we prevent something like Flight 3411 from happening again, we are finalizing a thorough review of our policies and will be making changes to avoid putting our customers, employees and partners into impossible situations due to policies we control.”

Senate Commerce Chairman John Thune (R-South Dakota), ranking Democrat Sen. Bill Nelson of Florida, Aviation Subcommittee Chairman Roy Blunt (R-Missouri) and ranking Democrat Rep. Maria Cantwell of Washington, received Munoz’s statement.

The United CEO also reiterated that the airline’s staff will be required to check into flights 60 minutes before departure. Munoz and the Chicago Department of Aviation (CDA) were questioned by senior Republicans and Democrats following the April 9 incident.

Also on Wednesday, the CDA sent the committee a letter vowing to help improve passengers’ experiences at airports in the city.

“As part of the review, at total of four Aviation Security Officers (ASOs) allegedly involved in the incident were placed on administrative leave on April 10, 12 and 19, 2017,” CDA Commissioner Ginger S. Evans wrote, according to the Hill.

United Airlines came under fire after a passenger named David Dao —a doctor — was violently dragged away from a flight from Chicago to Louisville. The video of Dao’s violent removal went viral, and Munoz issued an apology soon after. 

Dao’s attorney said earlier this month his client said he suffered a “significant concussion,” a broken nose and lost two front teeth.