I have been conducting both technical and management interviews for quite a few years now, and occasionally had to sit in a few of these interview as well. Recently just a few weeks ago, when I was sitting in the meeting room and conducting an interview with three other interviewers, one interviewer asked a question "if you encounter ..... this type of scenario, what would you do?"and I could not stop but start thinking that this type of question is useless at best and usually misleading. The reason is simple since the scenario in the question is hypothetical, thus the interviewee can fabricate an answer without worrying about any kind of constraints existed in the reality. I am not saying everybody will lie under this kind of circumstances, but the problem is you can't verify whether it is a lie or not, since the whole thing is fabricated. In most cases, I found that the interviewee will give you a perfect answer, or a solution that they would like to perform if they are working in an ideal world, I call this kind of answer - Phantom Read. If you buy into this kind of answer you get, you will probably end up hiring the person that the interviewee would like to be in the ideal world but not the actual person sitting in the room, in other words the Phantom.
So what is a good question then? A good question should always be based on the actual experience, sometimes a mere description of what they did could be the best answer you will need. Usually you can comfortably lead to this kind of question by simply asking about the past project experience, and then ask "As you mentioned ..... could you also tell us about what you did when ..... happened?" A follow up question like "If you get to do this all over again, what would you do differently to improve ..... " can provide further insight into your candidate's thinking process and self learning capability from their success or failure.