A concave parallel plate capacitance sensor has been developed to measure the two-phase flow void fraction for the purpose of objectively identifying flow regimes. The sensor has been used in conjunction with a two-phase flow loop onboard the NASA Lewis DC-9 microgravity aircraft, and data was recently collected. The void fraction time trace and probability density function, along with high speed video images of the flow were used to determine a more objective method of flow regime identification than what is possible through examination of video images alone. A set of criteria was developed to allow the identification of the flow regimes and their transitions through the examination of the void fraction probability density function. Against these criteria, flow regime transition models in the literature for microgravity gas-liquid two-phase flows were evaluated.