Gaia astrometry simulations results. From top to bottom: (a) derived inclination vs. simulated value; (b) fitted eccentricity vs. simulated value; (c) derived (blue) and simulated (red) astrometric semi-major axis vs. injected orbital inclination; the black dotted line shows the semi-major axis of the Gaia solution, a₀; (d) significance of the a_fit vs. simulated value; the black dotted line indicates the value obtained for the Gaia solution. In all panels yellow diamonds highlight orbits with inclination within 5° of an exactly face-on configuration.