What is the primary indicator for monitoring cabin pressure in the control system?

The primary indicator for monitoring cabin pressure in the control system is the cabin differential pressure indicator. This instrument measures the difference between the pressure of the air inside the cabin and the pressure of the outside atmosphere. It is essential for ensuring that the cabin maintains a safe and comfortable environment for crew and passengers, particularly at high altitudes where outside atmospheric pressure drops significantly.

Monitoring cabin differential pressure allows aircrew to detect any changes that might indicate a breach in cabin integrity or other issues affecting pressurization. Maintaining proper cabin pressure is crucial for preventing hypoxia, ensuring passenger comfort, and enabling the aircraft to operate safely at altitude.

In contrast, the other options do not serve the purpose of directly measuring cabin pressure. The cockpit radar display is used for navigation and situational awareness, the exterior atmospheric gauge measures outside air pressure, and the cabin temperature gauge tracks the thermal environment within the cabin rather than its pressure. Therefore, the cabin differential pressure indicator is the correct choice for monitoring cabin pressure in the control system.