Cabin Pressure

Cabin pressurization depends on maintaining a controlled relationship between cabin pressure and the decreasing atmospheric pressure outside the aircraft. As the aircraft climbs, the pressurization system regulates airflow and adjusts outflow valves to maintain the target cabin altitude while keeping the pressure differential across the fuselage within safe limits. Differential-pressure sensors monitor the cabin-to-ambient pressure, while absolute-pressure sensors support cabin-altitude and rate-of-change calculations.

These measurements change continuously during climb, cruise, and descent. The system must distinguish actual pressure changes from disturbances caused by vibration, airflow pulsations, valve operation, and temperature variations. Accurate, stable measurements help the controller make smooth pressure adjustments, minimize unnecessary warnings, and protect passenger comfort and aircraft structural limits.

Superior Sensor Technology’s ND Series supports cabin-pressure monitoring with differential models for cabin-to-ambient measurements and absolute models for cabin-altitude and atmospheric-reference sensing. A 2.25-millisecond update rate keeps pressure data current, while temperature compensation and optional digital filtering help maintain measurement consistency as operating conditions change. Together, these capabilities simplify system design and enable responsive cabin-pressure management throughout the flight.

Recommended Sensors

Common Device Features: 3.3V supply
Long-Term Stability is measured after first 12 months
Short-Term Error Band (STEB) is measured over 24 hours, after auto-zero

Common Specifications

Cabin Pressure FAQ

What is cabin differential pressure, and why must it be monitored?

Cabin differential pressure is the difference between the air pressure inside the aircraft and the ambient pressure outside. As the aircraft climbs and atmospheric pressure decreases, the cabin is kept at a higher pressure, increasing the differential across the fuselage. Continuous monitoring helps the pressurization system keep this differential within specified structural and operating limits while maintaining safe, comfortable cabin conditions.

What is cabin altitude, and how is it measured?

Cabin altitude is the standard-atmosphere altitude that corresponds to the air pressure inside the cabin. It is not the aircraft’s actual altitude. An absolute-pressure sensor measures cabin pressure, which the pressurization controller converts into cabin-altitude data. The rate of change of cabin pressure is also used to determine the cabin climb or descent rate, helping the system manage pressure transitions as the aircraft changes altitude.

What types of pressure sensors are used for cabin-pressure monitoring?

Cabin pressurization systems commonly use both differential- and absolute-pressure sensors. Differential-pressure sensors measure the pressure difference between the cabin and the outside atmosphere, while absolute-pressure sensors measure cabin pressure for cabin-altitude and rate-of-change calculations. The ND Series provides both measurement types. Multi-Range™ technology allows differential models to support multiple factory-calibrated pressure ranges with the same hardware, while absolute-pressure models provide fixed ranges for specific measurement requirements.

How do pressure sensors support automatic cabin-pressure control?

The pressurization controller uses pressure measurements to determine when and how much to adjust the aircraft’s outflow valves. Accurate, timely feedback helps the system follow the programmed cabin-altitude profile during climb, cruise, and descent while minimizing abrupt pressure changes. The ND Series provides a 2.25-millisecond update rate. Optional integrated closed-loop control can reduce external circuitry and shorten loop delays by up to 100 times, enabling more responsive pressure regulation.

How do vibration and temperature affect cabin-pressure measurements?

Engine and propeller vibration, airflow pulsations, compressor operation, and outflow-valve movement can introduce fluctuations that obscure actual changes in cabin pressure. Programmable digital filtering attenuates these disturbances, and selectable bandwidth allows engineers to balance noise reduction with system response. Temperature changes can also affect sensor offset, span, and overall measurement accuracy. The ND Series is temperature-compensated from −20°C to +85°C, helping maintain consistent pressure measurements across its specified operating range.