Definition 1 of 2
Definition
An electrical device that transmits angular position or rotation from one shaft to another remotely, using paired transmitter and receiver units connected by wires. The transmitter senses the angle of an input shaft and sends an electrical signal that causes the receiver to rotate to the same angle, allowing a remote sensor's reading to be displayed accurately on a cockpit instrument.
Plain English
A pair of small electrical units that copy angle from one place to another. One unit measures how something is turned, and the other unit turns to match, so a sensor mounted somewhere out in the airframe can drive a gauge in the cockpit.
Context Anchor
Seen in discussions of remote compass and flux gate compass systems, especially where heading information is sent electrically to an instrument display.
Derivation
From 'synchronous,' meaning 'happening together at the same time,' from Greek syn- (together) and chronos (time). The name fits because the receiver shaft turns in step with the transmitter shaft — they stay synchronized.
Why Pilots Care
Synchros are how data from sensors mounted away from the cockpit reaches the instruments you actually read. If a synchro fails, the gauge can freeze or read incorrectly even though the sensor itself is fine.
Analogy
Think of turning one knob and having a pointer somewhere else turn to the same position. The synchro is the device that helps send that position from one place to the other.
Intuition Check
Do not read synchro as just a general word meaning “things are synchronized.” In this context, it means a specific electrical device that sends position information.
Example Sentence 1
In the flux gate compass system, a synchro transmits the heading signal from the sensing unit to the indicator on the instrument panel.
Example Sentence 2
If the synchro fails, the heading display will freeze or show erratic readings even though the flux valve is still sensing correctly.