A dynamic flight model of a jet trainer aircraft (Aero L-39) is developed in MATLAB-SIMULINK. Using a six degree of freedom mathematical model, non-linear simulation is used to observe the longitudinal and lateral-directional motions of the aircraft following a pilot input. The mathematical model is in state-space form and uses aircraft stability and control derivatives calculated from the aircraft geometric and aerodynamic characteristics. The validated results from the simulation of aircraft mathematical model are used to estimate flying handling qualities of Aero L-39. This estimation is carried out for the stick fixed longitudinal and lateral characteristics. The handling qualities are rated based on both computational method and practical method. The damping and frequency of both short and phugoid period modes were determined in terms of aerodynamic stability derivatives [3] for both longitudinal and lateral stabilities and based on pilot's opinion rating by means of using Cooper-Harper rating scale. The handling qualities of the aircraft can be estimated
according to its class and flight phase, and then it can be specified in terms of flying qualities levels.