“Maybe everything changes when the weekend comes and suddenly all the non-transponding pilots climb to great heights?”
This is true; the aircraft get above 0 feet! At my strip, it is unusual to find anybody flying Monday – Thursday 8am to 6pm and Friday 8am to 1pm. On a good weekend everything is up. Most gilding clubs operate one day during the week and at weekends. I occasionally fly during the week and the situation is hugely different. It is normally possible to get a traffic service, the airspace is much less crowded and some classes of aircraft are almost entirely absent from the sky. Even at a weekend, at significant altitude, say 6 – 10k, there is less traffic, but CAS normally makes this impractical. I regularly fly my LAA machine at 7 – 10k over the more remote parts of the UK (with mode C).
I am not anti transponder; I have mode c and have helped several people fit second hand units to LAA type aircraft. However, with the current regulations and the current fleet most flying machines will not have one for the foreseeable future. Try to get the BGA to push transponders and you will get “not technically possible”. Try to get them to recommend FLARM + PCAS and you have a chance as it is both technically feasible and much less expensive. As collision systems come onto the market which will combine the two, we are moving in a positive direction.
Rod1