Cabin Pressurization in X-Plane is optional - if an aircraft is built in Planemaker without any regard for cabin pressurization, it will be considered perfectly pressurized by the simulation.
However, when an aircraft is built in Planemaker with provisions for pressurization, the systems have to implemented and operated correctly, or black-out will occur at high altitudes - provided you have told X-Plane so by selecting the appropriate option in the rendering menu. (The X-Plane rendition is the full black-out one would get at 18000ft.)
- Bleed air switch on/off (This provides the pressurization for jet and turboprop aircraft.)
- Altitude display/selector with cabin and aircraft pressure and a setting knob
- Cabin altitude, or
- Aircraft altitude
- Cabin VVI selector ("rate controller") - counterclockwise: zero, clockwise: maximum
- Cabin altimeter
- Cabin variometer
- Systems menu: max. pressure for the cabin - usually 6 psi and 6,000 ft cabin alt work fine
Cabin Altitude or Aircraft Altitude Selector?Edit
You need one control or the other, but not both. They are equivalent in operation, but there are some subtle differences in behavior.
With the "Set Cabin Alt" control, you set the cabin altitude you want the pressurization system to hold.
As you climb, the cabin altitude matches actual altitude until you reach the set cabin altitude. Then cabin alt stays at the setting while you continue to climb, until you reach the pressurization limit of the plane. The Aircraft Altitude readout in this control indicates the maximum altitude at which the system can maintain the set cabin altitude.
The "Set Aircraft Alt" control works the opposite way: you set the aircraft altitude at which the pressurization system reaches maximum pressure, and the cabin alt readout shows you what the cabin altitude will be at that point.
Note: Vacuum-driven instruments rely on cabin pressurization. They will fail if the cabin pressure drops too low (and if the aircraft has one, the "Low Vacuum" annunciator will light up. Use electrical instruments to avoid this. Alternatively, you could lower the value for required instrument suction.