itsresidualmate - thanks for the explanation. A useful thing to know just in case.
Maybe briefings could be reworded ("pull the oxygen mask so that at least X feet of tube is visible" might be helpful). Right now the instructions seem to be "pull this thing an unspecified amount - there's no way to tell whether you pulled it enough except that you'll become unconscious and may die if you didn't (thanks for making my point, D Guerrero!) - if you pull it too hard you may break it" All this is to be done while many people are panicking. Subsequent irrational upset is not surprising and might be reduced with a little rewording.