from the AAIB report into the mid air collision in December 2007
"Following the accident to G-AKUI and ZK-KAY, AAIB investigators discussed mid-air collisions involving recreational aircraft, and electronic conspicuity, with staff at the CAA’s Directorate of Airspace Policy. The Directorate staff explained that, although they perceived a widespread concern about mid-air collisions amongst participants in recreational aviation, they were also aware of strong opposition from aircraft owners to mandatory requirements to fit transponders, on the grounds of complexity, cost, and weight. For these reasons, proposals to mandate widespread carriage of Mode S transponders had been withdrawn, and more limited proposals had been put forward for consultation. These proposals did not amount to an effort to reduce the collision risk between recreational aircraft, but only to protect aircraft operating inside controlled airspace from collision with recreational aircraft."
Whilst this is the mentality, there will always be collisions between recreational aircraft.
Please don't take that comment at face value. There are genuine reasons why the recreational fleet has been contesting the Mode S hype from the CAA.
These include cost (up to £5k to fit a Mode S when the aircraft might be worth less than that) and practicality (no power source or battery life less than the length of a day's flying. There is little gain in safety except for the very short period when a commercial aircraft flies in areas where GA is prevalent - Class G. GA gets very little from that.
We were promised by the CAA a low-cost, low-powered Tx but this is years away. Add to that the cost of a PCAS and and that would wreck any idea of low-end aviation.
Don't ever think that we are hostile to appropriate use of technology - in the case of the Luscombe fatality, the pilot died, while the bigger aircraft landed successfully. It is likely to be the smaller aircraft that will come off worse.
But given that the ATSOCAS services are variable, carrying expensive kit will not give much in the way of safety. Look at the proposal for Jersey Zone, for example. In future when you ask for a Traffic Service it will be downgraded to a Basic Service - ie non-radar derived information.