Flight tests and measurements are usually performed for newly built or modernised aircraft utilised by the Polish Armed Forces. In the course of flight tests the airborne equipment is also investigated. The main goal of the performed tests is to verify tactical performance and to identify technical parameters of aircraft and/or equipment under examination. The airborne experimental data is also applied to the aircraft flight dynamics modelling, subsequently used for the design and construction of a flight simulator. The equipment is usually arranged of the following components: ̶ sensors/measuring devices capable of converting physical parameters into optical, mechanical, or electrical signals (indicators, transmitters, sensors, transducers); ̶ conditioning systems - intermediary devices used to amplify and/or adjust any signal gained to some required value or form; ̶ recording and storing devices (data recorders, cameras, etc.); ̶ devices applied to the decoding and processing of the acquired data (decoders, computers). Some selected problems of aircraft flight tests will be discussed in the paper. A brief description of the applied experimental apparatus will be provided first. Next, the attention will be focused on the experimentally gathered data utilised in the identification of aircraft flight dynamics characteristics and on the data applied to the evaluation of selected design parameters.