Loss of 1/2 stab
It tells me that the horizontal stab has a negative lift vector, and when half the stab is missing, the remaining side could not keep the nose from tucking under very rapidly. At least, not at approach speed.
Had it failed at descent speed, the crew might have survived a while longer, until they tried to slow down.
Incidentally, this accident set off a worldwide Aging Aircraft campaign to develop new inspection techniques for continued airwortiness.