SJI plane-of-sky velocities. Panel a: the SJI Si IV 1400 Å image (reverse colour) at 08:26:20 UT. The overplotted horizontal (green) and vertical (blue) lines represent two artificial slit positions where we obtained time-distance plots. Panel b: the time-distance plot for the vertical slit position (reverse colour). The features shown by blue arrows represent an untwisting motion of the jet spire structures. Panel c: the time-distance plot obtained from the horizontal slit position (reverse colour). The long dashed green lines are overplotted on threads of the spire of jet 2 and dashed blue lines are overplotted on threads of the spire of jet 4. These lines were used to calculate the plane-of-sky velocities.