Sustainable Aviation Fuel Act This bill establishes targets and standards for reducing greenhouse gas emissions from airplane flights and provides incentives for the production and use of sustainable aviation fuel. Specifically, this bill establishes a national goal to achieve a net 35% reduction in greenhouse gas emissions from flights by 2035 and net zero emissions by 2050. The Environmental Protection Agency (EPA) must establish a low carbon fuel standard for aviation fuels. Under the standard, the EPA must set annual targets in order to reduce certain greenhouse gas emissions associated with aviation fuel by at least (1) 20% by 2030, and (2) 50% by 2050. Beginning in FY2023, the Department of Defense must make a bulk purchase of an amount of sustainable aviation fuel that is not less than 10% of the total amount of aviation fuel procured for operational purposes. Additionally, the Department of Transportation must implement a program that offers grants and cost-sharing agreements for projects to produce, transport, blend, or store sustainable aviation fuel. The projects must be located in the United States.