Originally Posted by
fujii
I don't think I am missing the point at all. The FAF is marked on the instrument plate as a cross at around 4 - 5 miles out, well after commencing descent. To be at 4000 at the FAF, you'd need an aerodrome elevation around 2500.
Perhaps you're thinking of the initial approach fix. Anyway, the FMS knows where the aircraft is and will fly it accordingly.
Respectfully, from experience, I've witnessed a number of aircraft (having been issued with "go-around" instruction whilst above the final altitude restriction on the missed approach procedure) climb like rockets and only stop their climb when questioned/instructed by ATC.
So your FMS may be clever enough to work it out (effectively continuing to descend to the final altitude on the missed approach procedure), but that certainly isn't what I've seen.
Ps Not all airfields are as you suggest above. Where I work is at sea level and the FAF (yes I know what it is!) is above the final altitude on the missed approach procedure (on one of the runways anyway!)