Definition
An electrically powered compass system that senses the horizontal component of the Earth's magnetic field using a fixed sensor unit (the flux gate) mounted in a wingtip or tail where magnetic interference is low. The sensor detects the direction of the magnetic field and sends that information electrically to a remote indicator in the cockpit, providing a stable, slaved heading reference that drives instruments such as the heading indicator or horizontal situation indicator (HSI).
Plain English
A compass that uses an electrical sensor in a quiet part of the airframe to detect magnetic north, then sends that heading to a display in the cockpit. Because the sensor is mounted away from engines and electronics, the heading it shows is steadier and more accurate than a traditional float-and-fluid magnetic compass.
Context Anchor
Seen in instrument-system discussions, especially where the aircraft uses a remote compass sensor to feed a heading indicator or other cockpit display.
Derivation
Flux refers to the flow of the Earth's magnetic field through the sensor. Gate refers to the way the sensor electrically opens and closes the path of that magnetic flux to measure its direction. Together, the term describes a device that gates magnetic flux to detect heading, rather than relying on a freely floating magnet.
Why Pilots Care
It supplies stable heading data to flight instruments with fewer acceleration and turning errors than a direct-reading magnetic compass.
Analogy
It is like an electronic weather vane for magnetism: instead of pointing into the wind, it senses the direction of Earth’s magnetic field and sends that information to the cockpit.
Intuition Check
Do not picture a small floating compass card in liquid. A flux gate compass is an electronic sensing system, usually with the sensing part mounted away from cockpit metal and electrical interference.
Example Sentence 1
Before takeoff, the pilot checked that the heading indicator was properly slaved to the flux gate compass.
Example Sentence 2
During the instrument scan the pilot noted the heading from the flux gate compass system before beginning the turn.