TAD, if you look in detail at the two schemes, you'll also see a great difference in demographics. The CAA scheme is mature; when the NATS/CAA split ocurred, all pensioners were taken on by the new CAA scheme, so at the point the new NATS scheme had no pensioners. Therefore in comparison, the NATS pension scheme is very young; ask any IFA and they will tell you that in such a situation a scheme will invest in a larger proportion of higher risk, higher yield investments.