Resolution Advisory

A Resolution Advisory (RA) is a TCAS alert communicated with auditory advice to pilots that requires an immediate change in vertical flight trajectory as a result of a predicted confliction with traffic.

Runway Extended Centreline

An extension of the physical centreline of the runway, displayed on the radar map to the limits of the Terminal Area. It has very important uses when planning and carrying out the radar vectoring of aircraft for control purposes. It is usually referred to as simply ‘the centreline’.