Definition
An aircraft system that uses compressed air to power instruments, components, or controls. In light aircraft, the pneumatic system most commonly drives gyroscopic flight instruments such as the attitude indicator and heading indicator, using either an engine-driven vacuum pump that pulls air through the instruments or a pressure pump that pushes filtered air through them.
Plain English
A system that uses moving air to make certain instruments and parts work. On most small airplanes, it's what spins the gyros inside the attitude and heading indicators so they can show the pilot which way the airplane is pointing and tilting.
Context Anchor
Seen in aircraft systems discussions, especially when learning how certain brakes, flaps, landing gear, or other movable parts are powered.
Derivation
From the Greek pneuma, meaning breath or air. A pneumatic system is literally an air-powered system — it uses moving air the way a hydraulic system uses moving fluid.
Why Pilots Care
Understanding the pneumatic system lets pilots follow correct emergency steps when hydraulics fail, such as using stored air to extend landing gear.
Grounding Statement
Picture air stored under pressure, then released through tubes to push a part into position.
Intuition Check
Do not assume every aircraft power system is electrical or hydraulic. Pneumatic means the system uses compressed air to do the work.
Example Sentence 1
During the preflight runup, the pilot checked the suction gauge to confirm the pneumatic system was producing enough airflow to drive the gyro instruments.
Example Sentence 2
When the hydraulic pump failed, the crew used the backup pneumatic system to lower the landing gear.