This paper deals with estimating errors in the measurement systems during experimental tests of unmanned aerial vehicles in the wind tunnel. The instrumentation and technique of the calibration for measuring pressure parameters are represented. Features of the measurement in the wind tunnel are characterized. The transformation function of the measuring channel was proposed. The estimation of high-velocity head measurement errors has been carried out. Relative and absolute errors of velocity head were estimated. Errors in measuring airflow speed have been estimated. It is shown that the velocity of the airflow is the result of an indirect nonlinear measurement. Errors in determining coefficients of aerodynamic forces and moments are calculated and represented. The appropriate graphical dependencies are represented. Errors of calibrating coefficients during the experiment are calculated, Instrumental errors in measuring aerodynamic coefficients are calculated. The obtained results can be useful for tests of the unmanned aerial vehicles of the wide class.