Surely a 50:50 ratio would also require that an equal number of those women with the necessary aptitude actually wanted to do the job, and applied for it. They don't. It would also assume that women were equally encouraged by their schools, unis and society generally to join the military. They're not. It would also assume that they were equally educationally qualified. They're not. (I'm not being sexist, but just pointing out the low proportion of aero eng/eng degree courses made up of female students, and the lower proportion of girls taking the more relevant GCSEs and A-levels).