Downburst has been a potential threat for flight safety, especially during takeoff and landing, and has been identified as one of the most important causes of aviation accidents during these phases. Aircraft performance degradation in this phenomenon gives pilot a very little opportunity to control the aircraft correctly. Determination and evaluation of downburst destructive effects need a precise model of wind field in it. In this paper, flight data analysis and reconstruction has been presented when the aircraft was traversing through the downburst. In the first step, wind components and their gradients were determined using FDR outputs. Then aircraft performance degradation was computed quantitatively with a factor called F-Factor. In both accidents which were investigated in this research, F-Factor had values eventually resulted in accidents. Finally with modeling equations of motion and aerodynamic parameters, while using derived wind components, it was tried to find a suitable landing abort strategy. The results showed that best landing abort strategy during downburst encounter was to hold constant pitch attitude while using maximum engine thrust. This method was exactly applied on received data from NTSB and final results, in comparison with previous researches, completely verified the method. So, the required ability has been obtained for the analysis of FDR data.