Lets also remember that TCAS is not perfect.
Yesterday I had a B737 on right base with a helicopter inbound to the east of final, cleared on a segregated flight path. Helicopter & B737 were showing on Tower display & I had both visual.
I gave traffic info the B737 as required. Pilot response was to request confirmation of helicopter position as it was not showing on TCAS. Helicopter was approx 4 miles in 11 o'clock to the jet.
Again, everthing was being done correctly as per the new system, but the potential for problems was there should have only 1 other mitigator been absent.
