The Department of Transportation (DOT) is proposing amendments to its Air Carrier Access Act regulation on the transportation of service animals by air. Multiple parties from a variety of perspectives have called for greater regulatory clarity on what qualifies as a service animal, how airlines should classify emotional support animals (ESAs) for air travel, whether uncommon species should be allowed aboard planes, and how to mitigate health and safety risks caused by animal behavior. A key provision of the proposal is aligning DOT’s definition of a service animal with the Department of Justice’s definition under the Americans with Disabilities Act. This public interest comment summarizes the rulemaking, evaluates the proposal’s key provisions and analysis, and makes recommendations for improving DOT’s analysis of its proposed action. We specifically emphasize the need for DOT to explicitly evaluate alternatives to its preferred option and highlight the importance of distinguishing transfers from effects on social welfare.