TCAS - ATC uncertainty
Hey all,
I realise this probably should go in the "Questions" forum, but I have posted it here in an attempt to get more input, and if it gets moved there, so be it.
As ATC's in the UK, we have all had out TCAS briefs and seen the videos. Over the past couple of months a couple of uncertainties have come up from discussion and reviews of some incidents, especially the tragic recent mid-air over Germany.
Avoiding action given by ATC obviously can be provided by a turn or a climb/descent instruction. Over a few beers last night, a work mate of mine mentioned he has had a situation where jet in controlled airspace received a TA on traffic just outside controlled airspace below him, and wouldn't take a turn. He then went on to recount there have been several very similar situations seen in TC where drivers haven't taken an instructed turn, with a preference to "keeping the wings level" during a TA/potential RA.
It is this keeping the wings level I would like to have a healthy chat with you drivers about. Is this a standard procedure that we don't know about, or is it a "pilot perogative" in an attempt to visually aquire the traffic?
(The next bit isn't a fatalistic attempt to stir anything, or provide a journo with a great "what if" or "this is going to happen in the near future" to be splashed everywhere! Can we use it in a mature way please.)
If I could use a hypothetical situation for discussion, let's take case of a full hold at Heathrow (LAMbourne for instance). Due to it's proximity to the southbound DVR SID from EGSS that climbs to Min Stack level (with us holding traffic at Min Stack +1000ft). Hypothetically, take a full stack with every jet almost exactly on top of each other. For what ever reason, climbing EGSS DVR outbound busts his level, climbing straight at the stack. This is where the fun is going to start. Outbound causes RA between him and bottom aircraft in stack. One goes up, and one goes down. Now, I realise vertical climb profiles are monitored, and it not a case of "Oh !!!!!!" and pulling back on the stick going for as much vert as possible. However, bottom aircraft in hold RA's and climbs. What happens next? We know TCAS II talks between each other........will everybody in the hold get a RA?
As the poor controller sitting there watching this evolve, first thoughts are going to be "I can't go against a TCAS RA, I'm gonna start turning jets and passing traffic!" What are the responses from the flight deck going to be? Will the turns be taken? Another point raised was increasing speed in a attempt just to pull them apart?
Sorry if all this is a little deep. I'm not trying to be over the top.
Thanks.
J.