What is ASCPC on Boeing 737? (Air Supply Cabin Pressure Controller)

The Air Supply Cabin Pressure Controller (ASCPC) is a vital component of the Boeing 737 aircraft that plays a crucial role in maintaining a safe and comfortable cabin environment for passengers and crew. This controller regulates the cabin pressure and ensures that the pressure inside the aircraft remains at a comfortable level throughout the flight, regardless of changes in altitude.

The ASCPC continuously monitors and adjusts the cabin pressure during the entire duration of the flight, taking into account various factors such as altitude, aircraft speed, and temperature. It helps to prevent the sudden changes in cabin pressure that can cause discomfort or even health issues for passengers, such as ear pain or respiratory problems. By maintaining a consistent and controlled cabin pressure, the ASCPC contributes to a more pleasant and safe flying experience.

How Does the Air Supply Cabin Pressure Controller Work?

The ASCPC operates based on principles of pressure regulation and control. The system incorporates various sensors and valves to monitor and adjust the cabin pressure as required. Let’s take a closer look at the key components and their functions:

1. Cabin Pressure Sensor

The cabin pressure sensor is a crucial element of the ASCPC. It measures the pressure inside the aircraft cabin and relays this information to the controller. The sensor ensures that the controller is aware of any deviations from the desired pressure levels and allows it to make the necessary adjustments.

Boeing utilizes highly accurate and reliable sensors that provide precise readings even in extreme conditions. These sensors are designed to withstand the temperature and pressure changes encountered during flights and deliver real-time data to the ASCPC.

2. Cabin Pressure Controller

The cabin pressure controller is the central unit responsible for regulating and maintaining the desired cabin pressure. It receives inputs from the cabin pressure sensor and compares the readings with the preset values. Based on this information, the controller adjusts the air supply and ensures that the cabin pressure remains constant throughout the flight.

Boeing’s cabin pressure controllers are sophisticated electronic devices that utilize advanced algorithms to ensure accurate and reliable pressure regulation. These controllers continuously analyze the sensor data and make precise adjustments to the air supply system to maintain a safe and comfortable cabin environment.

3. Cabin Pressure Relief Valves

The cabin pressure relief valves are critical safety devices that prevent excessive cabin pressure in case of any malfunctions or emergency situations. These valves are designed to open automatically and release excess air to maintain safe pressure levels inside the cabin.

Boeing’s cabin pressure relief valves are carefully engineered to ensure proper functioning and reliability. They are capable of handling extreme pressure differentials and are tested rigorously to meet the highest safety standards.

The interplay between the cabin pressure sensor, the cabin pressure controller, and the cabin pressure relief valves ensures that the air supply system on the Boeing 737 always maintains the desired pressure levels, providing a safe and comfortable experience for passengers and crew.


The Air Supply Cabin Pressure Controller (ASCPC) is a critical component of the Boeing 737 aircraft that ensures the comfort and safety of passengers and crew during flights. By continuously monitoring and regulating the cabin pressure, the ASCPC prevents discomfort and health issues caused by sudden pressure changes. With the help of sensors, a sophisticated controller, and reliable relief valves, the ASCPC maintains a consistent and controlled cabin pressure throughout the flight.

Boeing’s commitment to safety and innovation is evident in the design and functionality of the ASCPC. The company’s focus on precision engineering and advanced technology enables the ASCPC to perform its vital role in providing a pleasant and secure flying experience.

For More: What is RVDT on Boeing 737? (Rotary Variable Differential Transducer)