Can you point me to the source statistics for this observation (genuinely interested and would be keen to take a look at them).
Merely my reading of accident reports. I do not recall seeing a formal midair breakdown.
I think all of the last 10 years' midairs (UK; about 1 per year) were below 1000ft, then we got one at 1800ft, and the last big one (the 4-person + 1-person fatal when doing an ILS calibration flight when hit from the side by somebody) is not yet classified but prob90 below 1000ft too due to the nature of the flight.
It is also readily apparent when flying.
Finally, there is a readily apparent correlation between how low people fly and whether they are radiating Mode C. When flying under a radar service, it is simply the case that no matter how hard you look and how hard one's passengers look, most reported targets are never spotted, but those that are reported "level unknown" (i.e. no Mode C transponder) usually turn out to be (when spotted) very low down; apparently around the 500ft-1500ft area. Such a correlation would not suprise me, given the attitudes to transponders (vis the "civil liberties" angle often put across by traditionalists in pilot forums
) among those pilots who are not touring much. What this means is that if you are under a radar service, you are much more likely to get a meaningful conflict report/warning (that you can act on) if you fly higher. What this also means is that if everybody was Mode C, the radar controller would not have to make most of the currently-useless reports
As to where they happened, this seems to be a mixed picture. Sure some were in the circuit. But others were during variously bizzare circumstances e.g. somebody doing orbiting for photo purposes while hit by an RAF Tornado. I think the "bizzare" ones are easily avoidable.