For Zeev, et al. Re: Columbia. NASA says they have compared this mission with all previous shuttle missions and found no unusual differences in tile damage. They also found that the computers not only made extreme inputs to control surfaces to maintain directional stability, but also fired its retro rockets in attempts to maintain directional and pitch stability.
I appears that when Columbia passed over the west coast, it began shedding structure much more substantial than just tiles. By the time it reached Dallas, Columbia apparently began to depart violently from scheduled heading and pitch attitude. The craft could not tumble and fly sideways at that speed and altitude without total loss of structural integrity. Maury Siskel