Plain English Meaning

It is a way for the aircraft to figure out where it is by sensing every movement it makes from the moment it started, then adding all those movements together. Because it does not need outside signals, it keeps working anywhere in the world.

Full Definition

Inertial Navigation (note: 'Intertial' is a misspelling of 'Inertial' as it appears in the source) is a self-contained navigation method that calculates the aircraft's position, velocity, and attitude by continuously measuring its accelerations and rotations from a known starting point, without relying on any external signals such as ground stations or satellites.

Context Anchor

Seen in instrument procedure and area navigation discussions where the aircraft’s navigation system must know its position accurately during or .