Re: FMS VNAV and altimeter setting.
Thanks Shore Guy
Based on your understanding of MSAW, it implies that leaving the altimeter pressure setting at 29.92 in error (the more common QNH mistake) will not enable an MSAW alert, whilst other QNH errors might be detected.
I am surprised at my own, and presumable others (due to no other response), lack of knowledge of how this valuable safety system works, and thus its dependence on correct altimeter setting procedures.
Many FMS cannot use GPS ‘geometric altitude’ due to problems of accuracy, but it is as you say good enough to provide an EGPWS alert. I was not aware that this was in commercial service, which aircraft type(s) use it?