Pandora wrote...
"It has been conclusively shown that differences in spatial ability between men and women (and indeed left and right-handed people) can be minimised with practise."
It is indeed true that the magnitude of the sex difference in average performance on certain tests of spatial ability can be reduced by practice. However, generally the difference cannot be totally eliminated - and there's the whole issue of differential sensitivity to practice effects as well.
The bottom line is that there are robust and well-documented sex differences in performance on certain tests of spatial ability - some favouring men (e.g. mental rotation), some favouring women (e.g. location memory). However, it’s not clear what implications these differences have for modern aviation.
One thing that’s very important to bear in mind is that for most tests the performance distributions for males and female overlap considerably. For example, for mental rotation a substantial proportion of women perform better than the male average – often about 30%. I would expect that the majority of female pilots would fall into this group.
I’ve actually done some research in this area myself (I’m a psychologist) and found an extraordinary amount of variation among females in performance on a 3D mental rotation tests. Females were more variable in their performance than males – which is unusual since males are the more variable sex in most other cognitive domains.