How the autopilot/flight director TCAS works

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Airbus has radically modified the interface that pilots use to react to resolution advisories from the aircraft's on-board traffic alert and collision avoidance system.

Reaction to a resolution advisory at present can only be flown manually, so even if the autopilot is connected when the advisory is generated, it has to be disconnected. The other anomaly is that the pilots have to transfer their attention to the resolution advisory indicator, which is relatively unfamiliar, to carry out a very delicate operation that demands precision reaction, and the result of this is often that the pilots over-react.

The Airbus solution is to integrate the TCAS resolution advisory with the flight director and the autopilot, so if the autopilot is engaged it will fly the resolution advisory, and if it is not the pilots have only to follow the flight director - with which they are totally familiar - to carry out a successful manoeuvre.

On this display the resolution advisory indicator is visible far right, and the flight director, as usual, consists of the vertical and horizontal cross-hairs in the centre of the primary flight display that the pilot is accustomed to use for manoeuvring guidance. The instrument, at the top, is informing the pilots that it is in TCAS mode, but the speed and navigation guidance remain active during the manoeuvre.

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