For the purposes of this Regulation the following definitions shall apply:

(1) ‘airborne collision avoidance system (ACAS)’  means an aircraft system based on secondary surveillance radar (SSR) transponder signals which operates independently of ground-based equipment to provide advice to the pilot on potential conflicting aircraft that are equipped with SSR transponders;

(2) ‘airborne collision avoidance system II (ACAS II)’  means an airborne collision avoidance system which provides vertical resolution advisories in addition to traffic advisories;

(3) ‘resolution advisory (RA) indication’  means an indication given to the flight crew recommending a manoeuvre intended to provide separation from all threats or a manoeuvre restriction intended to maintain existing separation;

(4) ‘traffic advisory (TA) indication’  means an indication given to the flight crew that the proximity of another aircraft is a potential threat.