To obtain a concatenation apparatus by which the position of an airplane can be transmitted to an information processor in real time without using hardware whose processing speed is fast.

Out of coordinate transformation expression in which 'graph north reference ground coordinates' are coordinate-transformed into 'true north reference ground coordinates' and in which 'the true north reference ground coordinates' are coordinate-transformed into 'the graph north reference ground coordinates', expressions which are found on the basis of installation positions of respective radar apparatuses 1-1, 1-2,... 1-n are changed into tables so as to be stored, and a computing operation is not performed whenever coordinates are transformed. In addition, data on an airplane is coordinate-transformed, the position of the airplane is corrected on the basis of the processing delay time in its coordinate transformation and on the basis of the delay time due to a radar search, and the data is sent to an information processor 2. In addition, whenever polling data is received from the information processor 2, the data on the airplane is received in a point of time which is prior by the portion of the processing delay time from the reception of next polling data, and the estimated position of the airplane is found.