Definition
A solid-state electronic system that senses the aircraft's pitch, roll, and heading using a combination of accelerometers, rate gyros (typically MEMS-based), and magnetometers. It continuously calculates the aircraft's orientation in space and feeds that data to electronic flight displays, replacing the spinning mechanical gyros used in older attitude and heading instruments.
Plain English
A small electronic box that figures out which way the aircraft is pointing and tilting, then sends that information to the glass cockpit displays so the pilot sees an accurate attitude indicator and heading.
Context Anchor
Seen in glass-cockpit attitude indicator and primary flight display discussions, especially when learning how modern electronic flight instruments get their attitude and heading information.
Derivation
The name simply lists what the system tracks: attitude (pitch and bank), heading (the direction the nose is pointing), and reference (the fixed framework — earth and magnetic north — that those measurements are made against).
Why Pilots Care
It supplies the attitude and heading data required for instrument flight; loss of AHRS data can force an immediate diversion or emergency descent.
Analogy
An AHRS is loosely like the sensors in a smartphone that know when the phone is tilted or turned, but built for aircraft and used to feed critical flight displays.
Intuition Check
Attitude does not mean mood here. It means how the aircraft is positioned relative to the horizon: nose up or down, and wings level or banked.
Example Sentence 1
After replacing the failed AHRS unit, the attitude indicator on the PFD came back online and showed correct pitch and bank.
Example Sentence 2
After a software update the AHRS realigned and restored accurate heading information.