Definition
An instrument that measures the strength and direction of a magnetic field. In modern aircraft, a magnetometer senses the Earth's magnetic field and sends that data electronically to the heading system, which displays magnetic heading on the cockpit instruments.
Plain English
A small electronic sensor that detects which way the Earth's magnetic field is pointing, so the aircraft's instruments can show an accurate magnetic heading.
Context Anchor
Seen in compass-turn and heading-system discussions, especially when an aircraft uses an electronic heading display instead of only a simple magnetic compass.
Derivation
From the Greek 'magnes' (magnet) and 'metron' (measure). Literally a 'magnet measurer' -- a device built to measure magnetic fields rather than just point along one like a simple compass needle.
Why Pilots Care
Supplies reliable heading information to the attitude and heading reference system, allowing accurate turns and navigation when the wet compass is unusable.
Intuition Check
A magnetometer is not the compass display itself. It is the sensor that detects Earth’s magnetic field and helps the display show a magnetic heading.
Example Sentence 1
The magnetometer, mounted in the wingtip away from electrical interference, sends magnetic heading data to the primary flight display.
Example Sentence 2
Modern glass cockpits replace the traditional compass with data from the magnetometer for smoother instrument flight.