Coherent change detection (CCD) technique is a kind of promising technique for current remote sensing system using RADAR, such as observation from unmanned aircraft observation system. Since a sensitivity of the target change depends on wavelength of radar system, higher frequency Synthetic Aperture Radar (SAR) is useful to detect a very slight change. On the other hand, detection of very slight change such as car track and collapse of resident area by using airborne high resolution SAR platform is very challenging due to very accurate flight pass control between before and after the change observation. We have hence developed a Ku-band airborne SAR system, with a spatial resolution of 10cm, and have developed high accuracy navigation system and installed them on the airborne platform. This paper presents the first results of CCD experiments. The experiments were carried on November 2007 in Nagoya area, using newly developed Ku-band SAR system curried on Gurfstream-II platform. We have conducted the experiments for 2 days and obtained 14 pass SAR images in total. We have achieved an accuracy of repeat pass separation as less than 10m and less than 3 degree of direction as a standard deviation. The CCD signal processing has been successfully implemented, and obtained with an average coherence of 0.6-0.9 in all images. As a result, a very slight change such as car track and trace of human activity can be detected. Detailed analysis result and discussion are presented in the paper.