Which is why in my paper about Flarm and PCAS etc., I suggest that winch launching gliding sites should consider having a PCAS at the launch point – it will alert to transponding GA aircraft approaching that are at first not in view of the launch point controller.
I knows it is not all the possible conflicts, but anything that helps avoid another tragedy is worth it in my view.
(Copies of the latest version available by email to identified and non-hostile correspondents.)
Chris N.