HEATHROW DIRECTOR
Air traffic controllers are far better equipped than pilots to see exactly what goes on. During the competitions at Wycombe I experienced on more than one occasion reports from commercial pilots of gliders "at the same level", "we have a glider above us", etc. Unlike the old primary radar, modern radars do not see flimsy aeroplanes too well so it is only sensible to have those aeroplanes properly equipped so that they can be seen.
This clearly shows that look out works and even airline pilots can actually see gliders on the very rare occasion that they use the windows for their intended purpose. There is a common misunderstanding amongst pilots that anything they see on or slightly above the horizon is above them, when the trafic is actually below them. NW of Henley you should expect that gliders will be above the inbounds as the base of CAS (5,500') allows this as there is lateral separation and not all airline pilots have got the hang of CDAs.
But if you are
far better equipped than pilots to see exactly what goes on
you will have known that and reassured them.
If you want to be pro-safety at all cost... get NATS to give you radar that does see all the traffic and not just some of it. Don't think you can just pass the cost on to someone else's budget, or are NATS going to pay for all the transponders?