My closest call was returning to my home base. I always have my Zaon MRX switched on and as I joined the circuit, it was registering traffic 3 miles away, 700 feet lower. I called Downwind 06. Upon turning Base, the target was 2 miles away, 700 feet lower. I called Base 06. As I flew along base, the target became closer. I turned on to final, called Final 06 and was shocked to see my Zaon suddenly start showing target 0.2 miles away, 200 feet lower, climbing.
I called over the radio to ask if anyone on the field had a transponder on, thinking this was possibly the issue. At the same time I intensified my scan trying to see if I could spot any conflicting traffic. Out of the corner of my eye, I caught some movement from underneath the root of my left wing and was shocked to see a motor-glider come shooting past me, climbing straight through my final. Vertical separation was at some point zero, horizontal less than 40 feet.
My first reaction was to call over radio 'what the XXXX was that?' At the airfield, the controller looked in the direction of my approach and saw the motor-glider come low over the field and called the pilot up - he was that close, that low, his registration could be read.
To both our surprise, the pilot not only responded, but when asked why he was breaching the rules of the AIP (no flying over the city at under 2000 feet) and why he'd not called up or observed my calls in the pattern, his response was that 'he was allowed to do that, low flying training is expected; in any case, he was not obligated to talk to anyone if he didn't wish to'.
Both the controller and I reported the incident, it was investigated and found that the pilot had taken off from an airfield around 15 minutes away using Runway 24. Because of this, he assumed that my home airfield would also be using Runway 24 and it didn't register to him that 06 was in use. His intention was to follow the river running parallel to the runway but that brought him straight through my final.
He confirmed he had heard me on the radio but assumed as I was landing, not going for a touch an go, that I wouldn't be a factor - which would have been the case, had my home field also been using 24. Moral of the story: You might have taken off using one circuit direction but another airfield in the vicinity might be using the reciprocal direction....