The studies are based upon the measuring records taken by the Japan Maritime Safety Agency at 12 monitoring points within the coverage of the Kita Kyushu Decca Chain during about one year (1969-1970). Additionally, supplementary measurements were carried out at two points during 72 hours. These observations were made by following data ; 6 days every month, every minute and 1030-1130 (daytime). Constant deviations of both each pattern and each point were obtained. The characteristics of these deviation were correlated each other at the next points in the Red and Green pattern. Monthly standard deviation showed that±1-3 cel corresponded to about ±10m near the base line except the point where to poor propagational conditions. Of course, the nature of the deviation suggested that the propagation velocity used were unsuitable, the reasons why of these phenomenon were presumably affected by the mountaineous profile along the each path. Especially a large amount of deviation of Purple pattern at Hososhima might be influenced by the nature of the route which across the sea and the steep mountains several times. The meteorological conditions will be affected the deviation and these introduced two types of variation. Approaching the front, high pressure and typhoon, a peculiar variation will be occured synchronously at several points.