To provide measurement data on a real time basis from a laser measurement device mounted on an air vehicle to a ground station. The laser measurement unit sequentially outputs laser measurement data during a measurement period in which the air vehicle flies along a straight line flight fairway (32). The transmission unit desirably compresses the laser measurement data when the laser measurement data is accumulated to a file size while the air vehicle flies along straight line flight fairway (32), and transmits the laser measurement data to the ground station. The transmission units does not transmit the flight state data obtained by the GPS/IMU to the ground station on the straight line flight fairway (32), but transmits during a measurement suspended period in which the air vehicle flies along a turn fairway (34).