The "Airport TIFIA Financing Certainty Act" aims to significantly expand the types of airport-related infrastructure projects eligible for federal Transportation Infrastructure Finance and Innovation Act (TIFIA) loans. It redefines eligible projects to include the construction or improvement of aviation-related facilities and equipment that facilitate, preserve, enhance, or expand air transportation, access, passenger/cargo movement, or airport user safety and security. Crucially, this expanded eligibility applies regardless of whether these facilities are revenue-producing or publicly accessible. The bill also streamlines the application process by exempting these specific airport projects from certain eligibility and waiver conditions typically required for TIFIA financing. Furthermore, it raises the threshold for simplified program administration from $75 million in eligible project costs to a $100 million TIFIA loan amount, potentially accelerating more projects.