The authors proposed "Space Scale" concept for measuring astronaut body mass in spacecraft on orbit. For the development of the flight hardware, accuracy/precision/operability verification tests under simulated microgravity are mandatory. We tested our device on a business jet flying parabolas to simulate microgravity. In addition to design constraints from microgravity, human factor engineering aspects also had to be dealt with. Methods (1) Mass was calculated based on (Mass) = (Force) x (Acceleration). (2) For Flight Test Series #1, a metal dummy mass of 9.37kg was used on parabolic flight tests. (3)For Flight Test Series #2, human subject mass was measured. (4) To eliminate acceleration noise from cabin vibration and air turbulence, data were rigorously filtered post-flight. Results With Flight Test Series #1, mass of the dummy was successfully derived with the standard uncertainty of 2.1 % for single measurement, and 0.7 % for the mean value of 12 measurements. Each measurement duration was less than 3sec., with rubber cord length reduction of 1 m. Conclusion The parabolic flight environment was a noisy acceleration field. Future studies should look more into human factor engineering aspects.