Extant airborne SAR has a lot of advanced function such as full polarimetry, multi-bands, etc. However it possesses several problems and has not been becoming practical use commonly in Japan. Therefore, the aim of our project is develop the following technologies aiming at the practical use of the airborne SAR. First, past flood disasters were investigated for function requirement arrangement and design equipped with the requested airborne SAR. Next, the SAR sensor (X-band) was improved based on the previous year's design, the proof experiment of the grasp technology such as ranges of the flood was conducted in the test field (Watarase storage basin) and the remaining issues for the real operation were revealed.