U.S. Immigration and Customs Enforcement Air Operations (ICE Air) is responsible for moving and removing detainees in ICE custody by providing air transportation services to Enforcement and Removal Operations’ (ERO) 24 field offices. We reviewed this program to determine whether ICE Air was ensuring the most effective use of its resources. Although ICE Air met its mission by transporting 930,435 detainees over a 3-1/2-year period, it could have used its resources more effectively. In fact, ICE Air may have missed opportunities to improve the program’s overall effectiveness even though it has identified some ways to reduce costs associated with detainee transportation. Furthermore, ICE Air does not capture complete and accurate data essential to support operational decisions. This occurred because ERO did not provide the planning, management, and reporting tools needed to operate effectively, and it does not have a mechanism in place to obtain feedback on how well its processes are performing. ERO management has not developed a data management plan, assessed staffing and training needs, or implemented formal policies and procedures. It also has not conducted a comprehensive analysis of current operations for making informed business decisions that will safeguard the program’s resources. As a result, ICE Air operated charter flights with empty seats and could have realized cost savings of up to $41.1 million upon determining optimum flight capacity. This estimate is based on the average of charter costs incurred during the scope period for the missions analyzed. Although the estimated potential cost savings will not be claimed as funds put to better use, it is an indicator of ICE Air’s potential for future cost savings.