Traffic avoidance turn - autopilot usage

[Manker]

I seem to remember reading a requirement for the autopilot to be disconnected when responding to an immediate turn request from ATC. Does anyone know where this requirement is published?

[BDiONU]

Suspect this thread might be better placed in a forum for the carbon based interface between ATC and the aircraft FMS ;)

BD

[WildWesterner]

I don't know if there are published directives but an Airbus 346 Capt told a bunch of us ATCO's recently that upon given avoiding action (if that's what you mean by an IMMEDIATE turn - differences between ICAO and CAA) he would just dial it into the autopilot, and had done so many times.

Apparently this is quicker than manually getting this particular aircraft into a turn but on the other hand the rate of turn would obviously be normal.

WW

[DTY/LKS]

Agree with WW
Recently told at LACC safety day that the majority use auto-pilot for an avoiding action turn.

[Dream Land]

How bout the book of common sense. :}

[West Coast]

I don't know if there is a regulation in your country with regard to it. If there is I imagine the reasoning behind it would have to do with differing bank angles between what a flight director will fly when commanded by the automation and what a human will fly. Generally 25 degrees vs about 30 or so for the carbon based one.

[vapourer]

According to UK AIC 99/2006 concerning "Avoiding Action - Pilot response to ATC; under "Initiation" it says that "with few exceptions the fastest way to initiate a turn or to initiate a pitch angle is to do so manually, applying control-wheel or side-stick inputs, as appropriate, after disengaging the autopilot. Consequent action should be to adjust the power as necessary; in many aeroplanes it will not be necessary to disengage the autothrottles.

Responses to "Avoiding Action" instructions should not be made by autopilot vertical or lateral flight control selectors because, due to the design of this equipment, the turn, climb, or descent that the Air Traffic Controller has requested and expects to see actioned will be initiated too slowly to serve the needs of the moment.

It is recommended that company Operations Manuals contain Standard Operating Procedures for the action to be taken in response to receiving an avoiding action instruction.

[Manker]

Thanks Vapourer - just what I was trying to find.

I must say that I am confused by the phraseology used by the CAA - "1.1 The purpose of this Circular is to remind pilots of what an Air Traffic Controller expects when the words ‘Avoiding Action’ are used, and to address - for the benefit of pilots and controllers alike - some of the issues that can affect the rate at which these instructions are acted upon."

The only information I have on my flight deck is Radar Phraseologies contained in the Aerad Flight Information Supplement. This states "Turn Left (or Right) immediately heading (3 digits) to avoid traffic".

Are the intentions of these two wordings the same?