Definition
In flight instrument systems, the means by which flight instruments are driven and supplied with the energy needed to operate. Common aircraft instrument power sources include engine-driven vacuum (or pressure) pumps that drive gyroscopic instruments, the aircraft electrical system that powers electric gyros and electronic displays, and pitot-static air pressure that drives the airspeed indicator, altimeter, and vertical speed indicator.
Plain English
What makes each flight instrument actually work — usually suction from a pump, electricity from the aircraft's electrical system, or air pressure picked up from outside the aircraft.
Context Anchor
Seen when learning how flight instruments operate, what can fail, and which instruments may be affected by an electrical or pump problem.
Why Pilots Care
Loss of power sources can disable critical instruments, forcing immediate transition to backup systems or partial panel procedures to maintain control.
Grounding Statement
If the supply of energy stops, an instrument may stop working or begin showing unreliable information.
Intuition Check
Power sources does not mean engine thrust or horsepower here. It means the supply that makes an instrument operate, such as electricity or air pressure.
Example Sentence 1
Before takeoff, the pilot checked each power source by confirming the vacuum gauge was in the green and the ammeter showed a normal charge.
Example Sentence 2
During the instrument scan, the pilot verified that both primary and standby power sources were available before entering IMC.