The author apologises that upon publication an obsolete version of figure 7, originating from a preliminary/test version of post-processing code, appeared in the original article due to an inadvertent mistake in the preparation of the final production files. Figure 7 in the original article should be replaced with the correct version of figure 7 as displayed below. There is no change in the caption of figure 7 of the original article and the same is repeated in figure 7 for clarity. The conclusions reported in the article are not affected.
Normalised spot leading-edge (
) and trailing-edge (
) speeds of turbulent spots identified in all the experiments conducted over (a) the flat plate and (b) the cone. In both the figures (
) and (
) show the lower and upper bounds of the 95 % confidence interval for normalised leading-edge and trailing-edge speeds, respectively.

