For anyone who has an interest in the practical side of cross-over alpha can I recommend (without reservation) a video produced by American Airlines Training Captain Warren Vanderberg. It is one of a series which he made, essentially dealing with performance issues in a variety of scenarios - unusual attitude recovery, wind shear, micro-burst, etc. One of the series deals with the issue of cross-over alpha and includes a set of video compilations from Boeing's Flight test division demonstrating the onset and both recovery and (initially) failure to recover. It is certainly the best articulated exposition of the phenomenon that I have seen and puts the whole subject in context. . .While the primary area of interest is obviously the 737, it makes the point that this is a generally alpha related condition and could be of concern to any aircraft operators. Beg, borrow or steal a copy, it is exceptional value.