Definitions

A clear and universally agreed upon definition for the term “Inertial Navigation System (INS)” is not possible. On the one hand the term INS is used as a blanket description for a wide variety of navigation sensors and systems of different design; and on the other hand, it is also used to describe a specific version of these sensors and systems! The term has also changed over the years as the technology has improved. What can be said with confidence is that all these systems work on a similar principle and for the same purpose.

Below is a list of commonly used terms that are used colloquially and interchangeably by pilots (if not by all designers, manufacturers and engineers) to mean very much the same thing, with differences in some of the detail. Where necessary two or more definitions are provided.

Inertial Navigation

a form of “Dead-Reckoning” that relies on accelerometers and gyroscopes to detect acceleration and velocity respectively along 3 perpendicular axes. An approximate 2 or 3 dimensional position can be constantly determined in relation to a known starting point, velocity and orientation.