Do you respondents have any authoritative references to back up your claims that TCAS is unreliable?
Comments of the sort logged by Donald Dunbar indicate a distinct lack of knowledge and professionalism for his part.
My post was NOT made for the sake of sensationalism, merely a statement of fact - and devoid of any racist comments such as posted by ATC Watcher.
Akin to Kaptain M's comments, I too have found in over a decade of operation, that TCAS of today is an extremely reliable tool in providing the position - in both the vertical and lateral axes - of other traffic.
Another re-reading of my original post would have one realise that as the other traffic was unidentified, the ATC had no idea in which direction it was heading, nor any radio contact with it.
The instruction to turn onto a heading of 220, was a 50-60 degree course alteration for the 747.
My estimate of less than 5 miles was being generous - it appeared to us to have more likely been closer to 3nm.