Definition
An instrument that displays the pressure of the air being supplied to vacuum- or pressure-driven gyroscopic flight instruments, indicating whether that air is flowing through them at the correct value to keep their gyros spinning at the proper speed.
Plain English
A small gauge that shows whether the air running your spinning-gyro instruments (like the attitude indicator and heading indicator) is at the right strength. If the reading is wrong, those instruments may not be reliable.
Context Anchor
Seen in discussions of vacuum or pressure systems that power air-driven attitude and heading instruments.
Derivation
Gyro is short for gyroscope, from the Greek gyros meaning a circle or turn. The gauge measures the air pressure that keeps these spinning instruments turning at the correct rate.
Why Pilots Care
Incorrect pressure means the gyro instruments may give false attitude or heading information, which can lead to loss of control in instrument conditions.
Grounding Statement
The gauge is not showing how the airplane is flying; it is showing whether the air-powered gyro system has the pressure it needs to work.
Intuition Check
Do not read “pressure” here as tire pressure or oil pressure. In this context, it means the air pressure or pressure difference used to drive the gyro instruments.
Example Sentence 1
During the runup, the pilot checked the gyro pressure gauge to confirm the reading was within the normal operating range before departure.
Example Sentence 2
A sudden drop on the gyro pressure gauge prompted the pilot to switch to partial-panel backup instruments.