Plasma flow velocity vectors in the 3D closed coronal loop under investigation. The location of the loop points in the high corona and the 3D geometry of the loop were determined using the LOS projection technique. Panel a: velocity vector v_ep, deprojected from the two Doppler LOS velocities measured by the two spectrometers at point 2. The epipolar plane (grey) is the plane containing the two satellites and the observation point. The vectors V_3D were constructed by the deprojection of v_ep on the tangent to the loop direction (panel b). The absolute values of the vectors are shown in Table 3.