FAA Advisory Circular 90-89C ("Amateur-Built Aircraft and Ultralight Flight Testing Handbook")

Department of Transportation
Federal Aviation Administration

Advisory Circular 98-89C
February 14, 2023

Amateur-Built Aircraft and Ultralight Flight Testing Handbook

Summary: This advisory circular (AC) provides suggestions and safety-related recommendations primarily to assist amateur-built aircraft and ultralight vehicle builders in developing individualized flight test plans. It also provides guidance for Experimental Light-Sport Aircraft (ELSA) flight testing after modifications to the aircraft. It provides recommendations and suggestions you can combine with other sources on test flying, such as the aircraft plan/kit manufacturer’s flight testing instructions and other flight testing data. This will help you develop a detailed flight test plan, tailored for your aircraft or ultralight vehicle and resources.