TRACON (novel) and TCAS issues
I looked for some previous discussion on this but didn't find any.
I've been reading Paul McElroy's novel TRACON (published in 2000). For those who haven't read the novel, which is about ATC, a key plot device is the notion that TCAS is occasionally dangerous because it only extrapolates the current movement of an aircraft and cannot know the intentions of ATC. For example, if TCAS sees two closely-spaced aircraft approaching each other, it may issue an RA to the pilots, not knowing that ATC has instructed the aircraft to level off at altitudes that avoid any conflict. Thus, the TCAS might give instructions that conflict with ATC's plan, and might actually increase the possibility of a midair rather than decreasing it.
The novel tempers this a bit with a bit about equipment at a few airports being defective due to the machinations of an evil senator, etc., but since the problem as stated in the novel seems kinda sorta plausible, I've been wondering about it.
So, my question to real controllers is: Does TCAS ever enter into conflict with ATC? If so, what kinds of circumstances lead to the conflicts, and how are they resolved? I was under the impression that TCAS is a net gain for safety, and even the novel does not assert otherwise, but it does claim that in a few cases TCAS can greatly increase the risk of a midair. Is this just a plot device for the novel, or does it have some basis in fact?
I read that a more advanced version of TCAS that could give turn instructions in addition to climb and descend instructions was in the works, but has been largely abandoned. Also, the novel points out situations in which TCAS might order a descent, not knowing that terrain awaits below, and that this is a risk also (which seems plausible). The novel asserts that (in the U.S.) ATC is not allowed to give any instructions to a pilot who has announced that he's following a RA, and I wonder if that is true, too.
(P.S.: I have no particular fear of flying and I like aviation, so feel free to give the straight story—no need for any reassuring talk about how safe air travel is.)