Hi IFLY_INDIGO,
what is the logic behind the pressurisation below the landing elevation????
Passenger comfort.
If the aircraft was depressurised before landing, you'd feel the aircraft's ROD (800ft/min) on your ears. Most passengers can cope with about -300 ft/min cabin altitude without feeling too much discomfort.
(It gives them time to equalise the pressure differential on their Eustachian tubes by yawning, swallowing etc.) If the +ve pressure differential on their ear drums builds too rapidly, the Eustachian tube will squash and equalisation is more difficult to achieve, causing greater discomfort.
+500 ft per min is easy to accommodate because the Eustachian tube is stretched open instead.