So just exactly what does disaster look like to a speaker? 

I think that  we can all agree that disaster can take on many forms when it comes to  delivering a speech in public. However, I think that if you are on a  stage and you lose your train of thought and can’t remember what you wanted to say next, then that can count as a speaking disaster. This is something that can happen to any of us at any time. 

We need to be ready to deal with it the next time that it happens.