A Native American firefighter had been employed by a federal agency as a forester for 25 years. During fire season throughout this period, he spent most of his working time fighting fires. The federal government authorized a retirement program granting an annual stipend for all firefighters credited with 20 years or more of service. To be eligible, employees had to apply for the credit within one year of the program's inception and prove that their duties included firefighting. The firefighter failed to make a timely application. Six months after the deadline had passed, the firefighter learned of the program, but his application for retirement benefits was denied. The firefighter challenged the agency's denial in district court, claiming that he had not received actual notice. He also argued that the unfavorable decision constituted unlawful discrimination in violation of a federal statute. The agency offered evidence that it had issued monthly personnel bulletins notifying all employees of the registration deadline. Additionally, the agency filed a motion for summary judgment, arguing that the firefighter had failed to make a prima facie case for disparate impact under the federal statute. The district court granted summary judgment for the agency. The firefighter has appealed the district court decision. What standard of review should the appellate court apply