Mike Raisler wrote:

TCAS installed on all transport category aircraft can "read" mode "c" or "s"
and determine if a climb or descent is needed to avoid the other aircraft.
The glider does not need to have TCAS installed, only a transponder, in
order for the other aircafts TCAS system alert for an avoidance manuever.


Ok, but the advice emitted by the TCAS in the other aircraft is based on the
assumption that the glider will keep its flying level and this is not true.