At our regular Atlanta neighborhood watch, we always have a senior police officer on hand to answer all sorts of random questions. Coincidentally, last week the topic of interest was "when do you call 911?" The answer is pretty much "for just about any reason". Examples given: if your car runs out of gas on a city street, if you see anyone in the neighborhood that looks the least bit suspicious, if you're locked out of your house...things that I would have never thought merited a call to 911. The officer was adamant that 911 (in Atlanta at least) is NOT for life-and-death situations only -- it's almost a clearinghouse/hotline for problems of any size.

All this is to say that I think passengers trapped in an airplane for 9 hours are clearly within bounds of exercising their 911 rights.