When to switch transponder on
Thread Starter
Joined: Aug 2000
Posts: 3,648
Likes: 2
From: UK
When to switch transponder on
With the Mode A/C transponder, we used to switch it on as part of the line-up checks. Presumably this was to avoid nuisance responses while we were taxying/holding on the ground.
We now have a Mode S (a GTX330 set up for ELS if it makes any difference) and my understanding is that has a ground mode that suppresses A/C. So should the SOP now be to switch on (ALT) the transponder before taxying?
We now have a Mode S (a GTX330 set up for ELS if it makes any difference) and my understanding is that has a ground mode that suppresses A/C. So should the SOP now be to switch on (ALT) the transponder before taxying?
Joined: Dec 2000
Posts: 2,132
Likes: 3
From: on the golf course (Covid permitting)
Bookworm, you will indeed find that an increasing number of airports the requirement to switch it on when pushing back an leaving it on until after parked.
I'm sure someone from LHR ATC will confirm that the Surface Movement Radar uses the txpdr code to track the aircraft on the ground.
Futhermore at LHR, we change the code after parking to 1000. I believe that with Mode S this will allow ATC to determine the registration when under tow etc, even when the txpdr is off.
I'm sure someone from LHR ATC will confirm that the Surface Movement Radar uses the txpdr code to track the aircraft on the ground.
Futhermore at LHR, we change the code after parking to 1000. I believe that with Mode S this will allow ATC to determine the registration when under tow etc, even when the txpdr is off.
Union Goon
Joined: Feb 2000
Posts: 1,097
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From: New Jersey, USA
Some airports now require transponder on prior to taxi anyway (pull up the atis for kbdl for example)
and furthermore I like seeing the tcas as I taxi. you will notice that the airacraft on the active runway go amber if you are taxing towards that runway. A further clue to avoid a bad day.
And last but not least, having the transponder on MIGHT allow a controll tower with ground radar to yell at a wayward aircraft with a proper callsign, rather than "aircraft approaching taxiway Alpha HALT." If I am lost I might not know what taxi way I am approaching, but my callsign I should know...
So to answer you questions, I turn em on immediately now...
Cheers
Wino
and furthermore I like seeing the tcas as I taxi. you will notice that the airacraft on the active runway go amber if you are taxing towards that runway. A further clue to avoid a bad day.
And last but not least, having the transponder on MIGHT allow a controll tower with ground radar to yell at a wayward aircraft with a proper callsign, rather than "aircraft approaching taxiway Alpha HALT." If I am lost I might not know what taxi way I am approaching, but my callsign I should know...
So to answer you questions, I turn em on immediately now...
Cheers
Wino
Joined: Jan 2005
Posts: 1,266
Likes: 0
From: uk
Eurocontrol guidlines are to switch 'On' your Mode S Transponder during taxying so that Airports with ASMGS can receive the enhanced info and provide better montoring on the ground, however leave your TCAS off until lining up (i.e. use XPNDR mode or equivalent).
The operation of many TCAS systems in a small area (like a busy airport) can cause saturation of the RF frequencies in use and require the TCAS unts to work a lot harder in decoding and responding to all the replies about. The use of such kit on the ground, where it is not really needed, has the potential to degrade the operation of TCAS onboard airborne aircraft.
So whilst it is nice to see traffic flying about as you taxy/cross runways etc., it is a bit anti-social. Leave it until line-up to have a quick look down the approach path, and even then remember that although it is unlikely to show traffic where there is none, it may not always show traffic when there is!
Lots more information at:
http://www.eurocontrol.int/airports/...ts_asmgcs.html
http://www.eurocontrol.int/airports/...leaflet_v2.pdf
The operation of many TCAS systems in a small area (like a busy airport) can cause saturation of the RF frequencies in use and require the TCAS unts to work a lot harder in decoding and responding to all the replies about. The use of such kit on the ground, where it is not really needed, has the potential to degrade the operation of TCAS onboard airborne aircraft.
So whilst it is nice to see traffic flying about as you taxy/cross runways etc., it is a bit anti-social. Leave it until line-up to have a quick look down the approach path, and even then remember that although it is unlikely to show traffic where there is none, it may not always show traffic when there is!
Lots more information at:
http://www.eurocontrol.int/airports/...ts_asmgcs.html
http://www.eurocontrol.int/airports/...leaflet_v2.pdf
