Fig. 11. (A) Vertical cross-section through a midwing plane in the 4 m s^-1 wake. Plotting conventions are as described in Figs 6 and 8, so relative bird motion is from right to left. The colour bar scaling is fixed to that established in the centre plane (Fig. 6), so saturation of the negative part indicates a relatively stronger stopping vortex contribution. (B) Vertical cross-section through the wingtip plane in the 4 m s^-1 wake. A and B, together with Fig. 8, can be compared with the three idealised patterns of Fig. 5.