To inject some facts;
On average 3 – 4 people a year die in mid air collisions in UK GA (that includes self launching motor gliders but not other forms of glider) (AAIB umbers)
Mid air collisions are one of the big three killers in gliding, and the BGA has recently issued a statement supporting collision avoidance devices being used to assist lookout.
If you read the accident reports, like the 2007 incident in the midlands, you will see that unless you have x-ray vision to see through the aircraft structure, you cannot see all the threats. In the 2007 incident the Luscome turned to avoid a micro and was “collected” by a turboprop doing 160kn. The Luscome pilot could not have seen the turboprop. Of the three aircraft only the TP had a transponder, but if the Luscome had had PCAS he would have at least had a chance.
In the UK about 50% of GA has a transponder. 15% of gliders have FLARM, but this is rising rapidly as it only became legal to use it in October last year.
Devices that detect both Mode C, Mode S, ADS-B and FLARM are going to be available early next year.
If you do a search on see and avoid you will find several studies. All are very negative about its effectiveness. I think we all need to work on our lookout, but we also need to consider if some tec can help us.
Rod1