Definition
A remote-sensing magnetic direction system that detects the horizontal component of the Earth's magnetic field using a fixed, pendulously mounted sensor (the flux valve) installed in a wingtip or vertical fin where magnetic disturbance is minimal. The sensor electrically transmits magnetic heading information to a slaved gyroscopic compass or heading indicator on the instrument panel, providing stable, accurate magnetic heading without the oscillation and turning errors of a standard wet compass.
Plain English
An electronic system that senses the Earth's magnetic field at a quiet spot in the airframe (like a wingtip), then sends that heading information to a steady gyro-driven compass on the panel. The pilot gets a smooth, accurate magnetic heading without the swinging and lag of a traditional liquid compass.
Context Anchor
Seen in instrument flying when studying heading indicators, remote compass systems, and aircraft heading displays.
Derivation
Flux' refers to magnetic flux -- the flow of a magnetic field through a material. 'Gate' refers to the way the sensor electronically opens and closes (gates) the magnetic field at high frequency to measure it. So a flux gate is literally a device that samples magnetic flux through electronic gating. Knowing this helps explain why the system is electrical rather than mechanical -- it doesn't pivot on a needle; it measures the field electronically.
Why Pilots Care
It supplies accurate, stable heading data free from acceleration and turning errors, supporting reliable IFR navigation and autopilot operation.
Analogy
Think of it like an electronic weather vane for magnetic north. Instead of pointing into the wind, it senses Earth’s magnetic field and sends that direction to the cockpit display.
Intuition Check
Do not picture a small hand-held compass with a gate on it. A flux gate compass system is a remote electronic sensing system that feeds heading information to cockpit instruments.
Example Sentence 1
Before takeoff, the pilot checked that the slaved heading indicator was tracking correctly with the flux gate compass system rather than running in free-gyro mode.
Example Sentence 2
Before departure the pilot verifies that the flux gate compass system is aligned and providing correct information to the autopilot.