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Old 10th Nov 2008, 13:45   #1 (permalink)
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Use of transponder on the ground

It does not give this as a requirement in our SOPs.

It does mention in many aerodrome booklets that transponder use is required during taxy.

There are many large airfields I visit in Europe and the Middle East and Asia where I am told by the trainers it is required (even though this is not mentioned in the booklets or the Jeps area supplement).

Anyone know where this is written please?
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Old 10th Nov 2008, 15:07   #2 (permalink)
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Don't know where its written, but its down to the new generation of surface movement radars (radar in this context is probably the wrong word!) which rely on transponder returns to generate the ground movement picture. Hence no transponder - No display of traffic to the controller.
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Old 10th Nov 2008, 17:24   #3 (permalink)
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Can the use of Transponder on the ground be the cause of a TCAS TA/RA or is there a special "ground mode"?

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Old 10th Nov 2008, 17:32   #4 (permalink)
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In FRA it is done by software and they had a long way to go before this feature was implemented. So before the software was able to link the callsign to the blip it was just a blip without any further information.
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Old 10th Nov 2008, 17:40   #5 (permalink)
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It's mode S that most of the modern systems use. Although operating procedures are slowly harmonising in some regions, they could hardly be considered to be standardised. Afraid the best place to look is going to be the relevant AIP pages.
Old 10th Nov 2008, 17:49   #6 (permalink)
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Originally Posted by FLX/MCT
Can the use of Transponder on the ground be the cause of a TCAS TA/RA or is there a special "ground mode"?
Private pilot speaking...I understand that most modern systems automatically switch to TA ONLY below 1000ft RA to inhibit nuisance warnings. I'm guessing that the system logic would look at the altitude and speed of the target to determine if it's on the ground, but that's pure speculation.
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Old 10th Nov 2008, 18:41   #7 (permalink)
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Spot on Check Airman.

FLX/MCT- while taxying you can turn the TCAS off while leaving your transponder operating if required by local procedures.

Speaking only for Airbus their FCOM 1.34.80 states in part that "... if windshear, stall or GPWS are triggered or aircraft below 500ft agl all TCAS aural messages are suppressed." (minor alt differences depending on whether climbing or descending).

Drivers of other types can speak to their specific aircraft.
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Old 10th Nov 2008, 21:17   #8 (permalink)
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TCAS/ACAS have no logic for determining if an aircraft is stationary or on the ground.

Warnings are suppressed as already pointed out.
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Old 10th Nov 2008, 21:51   #9 (permalink)
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Suppressing the TCAS RA is of course dependent on your Radio Altimeter, how else would it be done on any type?

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Old 10th Nov 2008, 22:42   #10 (permalink)
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I have started to always put the transponder to XPDR when the push/taxi starts because I don't bother remembering the airports where this is a requirement or not.

If the airport isn't equipped with this new transponder surface monitor system (A-SMGCS?) I have been told that "my" squawk won't bother anyone.

And the data sent out are not capable of trigging TCAS equipment (XPDR-mode)
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Old 10th Nov 2008, 22:47   #11 (permalink)
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Just a little insight from Air Taffic here.

If you are operating on an airfield that employs ground movement radar. Transponder use can be required, in which case the radar picks you up and identifies you on the blip on the airfield layout they have. Used at places where low vis often occurs, or large airfields to prevent collision and to increase efficency.

In terms of airfields not employing surface movement radar, the radar room doesn't get interference from your transponder being active whilst on the ground, as SSR radar supresses transponder codes on the ground, or airfields would just be a haze of transponder codes.
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Old 11th Nov 2008, 09:01   #12 (permalink)
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Can the use of Transponder on the ground be the cause of a TCAS TA/RA or is there a special "ground mode"?
A Mode S transponder includes an on-the-ground status flag in its reply. Thus if you have Mode S, you can simply leave it on.

A Mode A/C only transponder has no such output, so it should be switched on only for departure and off again after landing.
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Old 11th Nov 2008, 09:14   #13 (permalink)
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ACAS on the ground

Guidance can be found here http://www.eurocontrol.int/msa/galle...date_Nov07.pdf in the Eurocontrol Bulletin 9.

Other bulletins can be found here EUROCONTROL - ACAS II Bulletins and Safety Messages

All well worth reading.

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Old 15th Nov 2008, 01:27   #14 (permalink)
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Flying out of Amsterdam I know its mentioned somewhere in the Jepp plates in the airport briefing and ATC well call you on it if you do not have your transponder on XPDR mode as soon as you start taxiing.
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Old 16th Nov 2008, 07:20   #15 (permalink)
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I have come across airports that tell you to turn it on on the ground, and some airports that specifically tell you to turn it off. Some even state the requirement in the ATIS.
By 'it' i mean the transponder. TCAS should always be off on the ground, so you should use the 'auto' position on your box, or 'xponder'.
I guess the safe way would be to use the transponder on the ground, and let ATC tell you to turn it off if it bothers them.
My airline has put a line in the before start checklist and in the shutdown checklist for remembering to turn it on before push-back and off when at the gate.
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Old 16th Nov 2008, 14:09   #16 (permalink)
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From a number of sources [Eurocontrol ++] we have collected the following:

Advanced Surface Movement Guidance & Control System (A-SMGCS) is in an operational test phase at CDG, VIE and MUC but has also been installed (or are under installation) at a bunch of other european airports like: CGN, LYS, TLS, MAD, Barcelona, Oslo, Stockholm, Prague, FCO, Malpensa, AMS, Riga, LGW, LHR, BRU, FRA, HAM, DUS, Palma De Mallorca, CPH, Zurich, Geneva, Paris Orly.

As I understand it, Eurocontrol likes you to turn it on from the time you request push.
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Old 30th Nov 2008, 15:45   #17 (permalink)
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This just in:

To: All airlines operating into the United Kingdom
Dear Colleagues,
This message is being circulated to highlight an amendment to the UK AIP with regard to the requirement for use of Squawk A2000 on ground with effect from 12 February 2009. In essence the change seeks to harmonise the use of Squawk A2000 on ground as follows:

"Unless otherwise instructed by ATC, Mode S transponder equipped aircraft on the aerodrome surface should select Mode A code 2000 when under tow; or parked and prior to selecting OFF or STDBY."
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Old 1st Dec 2008, 17:14   #18 (permalink)
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if u have TCAS, just select the mode XNDR or ALTOFF NOT TA/RA.
It is especially important during low vis weather,so controller can track your progress.TARA only when entering runway in use.It is nerve recking to see alt reporting of an aircraft taxiing on // taxiway when you are taking off in low vis conditions.
If it is not written on your Jepps, you dont need to do it unless of course your SOPS require you to.


Last edited by Boingboingdriver; 1st Dec 2008 at 17:27.
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Old 1st Dec 2008, 17:25   #19 (permalink)
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Really depends on the kit you have equipped. Ours for example are set in AUTO and do as Mode S Transponders should: set the ground flag when on the ground so you won't get any altitude reports from them.
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Old 1st Dec 2008, 17:26   #20 (permalink)
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Miles Magister post #13 with it's links explains the scenario as best as possible.
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