Originally Posted by
Mtnrunner
Altitudes prior to the FAF are not MDA’s so I would say it’s +/- 100 until the FAF like any other altitude after the IAF (or prior). Then it would be +100/-0 after the FAF to the MAP. Better to stay on the +100 side anytime though.
Whether an at-or-above altitude on a step down fix is MDA is irrelevant.
An underlined altitude has nothing to do with practical test standards; it's a requirement of the approach. It doesn't matter if you're taking an instrument checkride or flying an instrument approach. The same requirement applies. Maintaining altitude in general has plus or minus tolerances, but hard altitudes on an approach do not offer those tolerances; you can be high, but not low.