TA/RA, ATC on ???

[roljoe]

Hi, a quick one,

what's the recomended mode to be selected while taxiing ????

Heard so many versions...I'will appreciate the controllers point of vue..

rgds

[kontrolor]

the transponder? on of course

[roljoe]

Thanks..anyway not so helpfull...:E

between..ATC ON..ATC ALT...TA Only...TA/RA..

What's the best mode considering the ground radar...this to avoid annoying warnings for them...for us in the cockpit..any selected mode remains OK...

[fellman]

This issue is covered in Eurocontrol's ACAS Bulletin No. 9 available at
http://www.eurocontrol.int/msa/gallery/content/public/documents/ACAS_Bulletin_9_Jul-07.pdf

Quoting from the bulletin:
"Should TCAS be operated on the ground?
The Advanced Surface Movement Guidance and Control System (A-SMGCS) is to be introduced at a number of European airports. To enable A-SMGCS detection, aircraft must be operating their Mode S transponders, at least from the pushback and until reaching the stand on arrival. TCAS also relies on Mode S technology and for this reason TCAS and Mode S control panels are usually combined in a single unit on the flight deck. Experience shows that TCAS is sometimes turned ‘on’ and turned ‘off’ at the same time as the Mode S transponder. Except for turning TCAS on for a short period of time before crossing an active runway to double-check for the presence of any aircraft on approach, this should not be done for the following reasons:
TCAS II is not designed to provide any safety benefits for aircraft on the ground: the collision avoidance function is not active before being airborne and the TCAS traffic display does not depict intruders detected on the ground (Note: due to erroneous transponder data, some aircraft on the ground may be displayed).
TCAS II routine operation on the ground degrades safety. Performances of the ground surveillance equipment (e.g. SSR, A-SMGCS) and of the surveillance by airborne TCAS II units can be compromised if there are significant numbers of TCAS II units operated on the ground. As a result, ATC and the operation of airborne TCAS II could be adversely affected.
(For more details, refer to www.eurocontrol.int/msa).
To address these issues, ICAO recommends in PANS-OPS (Doc 8168) and the ACAS manual (Doc 9863) not to operate TCAS II while taxiing.

1. At the gate: Transponder OFF/STBY, TCAS OFF
2. Pushback request: Transponder ON, TCAS OFF
3. Approaching holding position: Transponder ON, TCAS ON
4. Vacating runway: Transponder ON, TCAS OFF
5. Fully parked at the gate: Transponder OFF/STBY, TCAS OFF"

[Tarq57]

Can't be very helpful myself, sorry, just don't know enough about procedures around the world.
It probably varies between aerodromes where ground radar is used, and those that don't have it.
Mine falls into the second category, and the transponder should be SBY or OFF on the ground, to avoid radar clutter. Most of the aircraft seem to have a gear operated sensor that automatically inhibits it when weight is on the gear; the transponder turns on at liftoff (or sometimes gear retract).
As to ACAS, I believe TA/RA mode selection choice should be in your airlines' operating manual. RA mode close to the ground is more likely to trigger "false" avoiding action, I believe a lot of operators specify TA mode below about 1000ft.
If in doubt as to transponder selection when taxiing, ask the controller. At worst you'll get a "gee, what a dummy, it's right there in SUPP 2.34-7a, published a week ago, replacing NOTAM B17053/08, which modifies AIP Chart blah blah" type response. (Don't you guys read the 20 pages of NOTAMS we publish just for you before each flight?) The more likely (I would hope) response would be "OFF, please" (or v/v)
ACAS mode? Read your operating manual/ask a training captain or someone at ops.

[roljoe]

Nicely worded...Tarq57..:E have a nice week-end..m8

and thanks fellmen for the details...