The descent mode is activated when the airplane descends 0.25 psi below the
selected FLT ALT. The cabin begins a proportional descent to slightly below the
selected LAND ALT. The controller programs the cabin to land slightly
pressurized so that rapid changes in altitude during approach result in minimum
cabin pressure changes.
While taxiing in, the controller drives the outflow valve slowly to the full open
position depressurizing the cabin.
However my (old) FCOM says also:
LAND ALT (landing or destination airport altitude).
With regard to the tech explanation it makes more sense IMHO to dial in the rwy elevation.... but +/- 25 ft, who cares?
Rgds
Ah, Tomaski was faster when I was typing
