Time series data of aerodynamic characteristics obtained by flight tests have large variances compared with data obtained by ground testing tools such as wind tunnel tests and numerical simulations. It is necessary to examine the uncertainty of the data obtained by flight tests in order to minimize random and systematic errors. We investigated on-board measuring instruments of the aircraft, and analyzed systematic uncertainties of the aerodynamic coefficients obtained by the flight tests using the JAXA Flying Test Bed ``Hisho''. This paper discusses the result of the systematic uncertainty analysis and the contributing factors to the uncertainty of aerodynamic coefficients.
