an incident in the circuit witnessed by me was scary, although I doubt both pilots would have continued as they were if they didn't hear my call
I was inbound in a Drifter and approaching the downwind leg - being lower and with the spectacular vision afforded by the Drifter, I immediately looked for the ultralight aircraft that had called 'downwind', seeing it about a third of the way along the downwind leg
I then heard another aircraft call 'turning downwind - not visual with aircraft on downwind leg' - I then looked across to base and saw a GA aircraft turn onto downwind - and he seemed a bit closer in than normal
the problem was exacerbated by the fact that the GA was higher than the ultralight, and as such the ultralight was probably not visible because it was below his windscreen - plus, his left wing was down during the turn onto downwind so that didn't help with his lookout either - the only chance he had to see the ultralight was on base, and he didn't see it - I guess he expected to see it as he went along downwind, but he may have caught up to it before he saw it...
add to that the fact that the GA aircraft was faster, so I could see that it was catching the ultralight fairly quickly
my radio call was 'GA aircraft callsign, the ultralight is at your 12 o'clock low' - the reaction was instantaneous - one went left, the other went right, both calling to announce they were departing the circuit
could have been nasty... I suspect that in the mid-air situation above, the aircraft behind did not have visual on the other aircraft because he was below his windscreen
the only other fly in the ointment was that neither pilot called when they both reacted instantly to depart the circuit - what if they both turned the same way?
anybody wanting to giggle about the strobe and landing light I just fitted to my Drifter, go right ahead - but nobody is going to miss ME in (or approaching) the circuit
BP