Purpose: This document sets forth the characteristics for a selfcontained Electronic Chronometer specifically designed for installation in all types of commercial transport aircraft.

The intent of this document is to provide general and specific design guidance for the development and installation of a self-contained Electronic Chronometer primarily for airline use. As such, this guidance will include the details necessary to provide the desired operational capability and the standards necessary to achieve interchangeability.

Equipment manufacturers should note that this document aims to encourage them to produce maintenance-free, highperformance devices. They are at liberty to accomplish this objective by means of design technique they consider to be the most appropriate, as their airline customers are interested primarily in the end result rather than the means employed to achieve it.