Where they microlights, you reckon? What are the rules for the use of transponders by microlights in the UK?
Here in Italy I encourage people with a microlight to have a transponder with Mode C on board, and to keep it on ALT, always, even if they are not in radio contact, just because of the added bonus of being seen by TCAS in case of straying into CAS by mistake.
I doubt that weight-shifting trikes would have a transponder, though. And gliders with that weather, difficult, unless you were just above a field with a winch, but they should be published.
Ciao, Luca