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?