Bertie,
Very good point about you being on the right - for the sake of the example, I probably should have made the traffic in your 2 o'clock, right-to-left
However, I will always give way to traffic, even if it's on my left, unless I can clearly see that he has seen me and is taking avoiding action - I know there's a very good chance he hasn't seen me.
That aside, the point of my question was that you
don't have the other traffic in sight. You know where he is laterally, but the only height information you have is unverified.
As IO540 says, the safe assumption is that the other guy's transponder is working, and it's worth taking some avoiding action (especially if in IMC) if the unverified altitude is the same as yours.
More interesting, though, is the case where ATC say he's 500' below you, unverified. What if his transponder is 500' out? Would you take avoiding action? Personally, I wouldn't... but I do sometimes wonder whether I should.
FFF
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