fireflybob - you are indeed correct, but it isn't exactly a difficult thing to do... and surely ensuring you have copied the QNH correctly in the first place is an addition to safety?
anotherthing, lots of things are not "a difficult thing to do" but sometimes they don't get done or get done incorrectly. I think this is almost the crux of the issue. Psychologically if you have a mindset that you have already done something correctly the tendency is not to recheck. On the other hand if when you call for taxi ATC say
new QNH is XXXX, I'm willing to bet most pilots will recheck the subscales. Also remember that most transport a/c have a comparator system between Capt and Fo Altimeters so if they is a signficant disagreement between indicated altitudes the system will flag this up.
I am with Jumbo Driver on this but as he had already said I would like to see the statistics for altitude busts on
departure which have been caused by QNH incorrectly set. Also the breakdown on whether ATIS was available at the time (some airports don't have ATIS). Also bear in mind that some operators depart with handling pilots altimeter set to QFE! Another cause for errors!
I think this has become a circular arguement! We need to get back to some critical thinking! The question is how can we ensure that the correct QNH is set prior to departure? My answer is train the pilots to ensure that apron elevation is indicated having set QNH! This should have been done thoroughly during
basic training and should be covered during routine proficiency checks.