Originally Posted by
ShotOne
1000ft is very late in the day to be deciding which altimeter you should be looking at!
Just to confirm, this is the last of a number of altimeter cross-checks (top-of-drop, every 5000' above 10,000' and every 1000' below). If the opposite Altimeter reads lower, you don't start flying a cross-cockpit scan, you mentally adjust for the discrepancy whilst flying on your own. You could not do this much earlier because the errors between altimeters can increase with height (hence the absolute requirements for an altimeter cross check before entering RVSM airspace).
E.g. On an ILS with a DH of 200'. At 1000' I compete a cross check and find that the other Altimeter reads 960' (within limits). If I were to ignore this and the other Altimeter is correct I would erode my safety factor by 10%. Instead, I mentally adjust my Altimeter indications to make my decision at 240' (200' on the other Altimeter and, for all I know, agl):