Goeff,
It is hard to keep one's hair on whan such dunderheaded judgements are floated around as if they are thought out!
To your point, clearly moving obstacles are a problem. How is AVAD helpful there?
The update of the permanent data base is obvious, put them into the base at HW, monthly. The data base update in the operations room for transient rigs (if they are in a single spot for the duration of the flight) might be OK, and it would also be possible to cook up an operations protocol where a moving rig is assumed to be inside a large box for the duration of the day, and that box is programmed into the data base. This is one way to make it work, mostly. I agree that human error might creep in here, but nobody is saying to abandon what we do now and just trust the EGPWS with full responsibility for obstruction clearance.
What I see as the issue here is that NOBODY is running into mobile rigs, but yet some will reject the EGPWS until we somehow depict them. Why dont we fix what we are currently doing wrong. We are descending into the water or running into terrain, yet people like HC are rejecting EGPWS because they have some very nice need to perfect that last 1%.