Can agree with someaspects of Chevvron's argument, however, I'm all for encouraging pilots with transponder equipped aircraft to use the bloomin' things! Especially the Mode C. It can reduce the chance of a close call or, God forbid, mid-air, with a TCAS equipped aircraft. The selection of a wrong QNH is often a cause for infringement of the TMA, together with poor situational awareness. I have also seen many CTZ infringements, spoken to the pilots in question and received an excuse that they were "A little lost"! My response is use the radio! Call SVFR, Northolt or D & D on 121.5 if unsure of position. We would rather identify an aircraft and steer it in the right direction than have to avoid it, hold departures and/or break off arrivals. It can also save a lot of paperwork!
A17