Hi again
JeroenC: I forgot to add in my original reply that I think it is a
very good thing that you (we!) are scared of mid-airs... this keeps us alert and is perhaps why they happen less than they otherwise might!
I appreciate that you yearn for a technology solution, but there are many aircraft that don't (for now) carry transponders so you can't rely on TCAS in VMC and just leave your head in the cockpit... gliders for a start often don't have weight / battery power sufficient for transponders (although there are new light weight low power transponders coming on the market for Mode-S). Maybe one day we will have a universal ADS-B environment, but not yet so until then keep your eyes up and looking out!
Andy
