Originally Posted by
surplus1
Excellent question. The simple error of forgetting to change from QNE to QNH, at night, over water, and under the right conditions could easily cause you to descend until you strike the surface. A functional E-GPWS or a good radio altimiter might avoid that, but over the ocean either warning might come to late or not at all.
My bold ...
Agreed, but on this night that would only account for a 100' error (if I've done the sums right). Altimeter erroneously set maybe, otherwise we may need to look elsewhere.