Question id 155 - Aircraft General Knowledge - Airframe, Systems, Powerplant - ATPL - Airline Transport Pilot license

A descent must be initiated to prevent the oxygen masks dropping when Zc reaches 14000 ft.
The aircraft has to climb to a higher flight level in order to reduce Zc to its initial value.
DELTA P will rise up to its maximum value, thus causing the safety relief valves to open.
The crew has to intermittently cut off the incoming air flow in order to maintain a zero Zc.

Training tests and timed exam simulations ATPL - Airline Transport Pilot license