A few weeks ago a departure made a turn by themselves in response to "TCAS" (that's what the pilot said). Now this is not the first time I've seen this happen.
There was traffic (no Mode C) well below them in the circuit of another airfield, but this had a few of us scratching our heads. The pilot was asked to confirm what he said ...."Uh yeah, we had traffic on our TCAS...uhhhh, yeah the TCAS went off" I wish the Departure guy who was working had made the pilot spell out if they received an RA or TA, but unfortunately the pilot was being a little cryptic, and there was a bit going on.