In contrast, the manoeuvre in Scenario 2 resolves the conflict with the unseen 2 o'clock traffic.
Because you haven't come close enough to the other traffic to trigger an RA yet. That's why your scenarios are different - the aircraft are in different positions...
Originally Posted by FullWings
In your scenario No. 3 you're assuming that the traffic you can see is the one that has generated the RA...
I am not assuming anything at all.
No? Then I'm having problems with the meaning of this sentence:
..you get a climb RA for your visual target at 10 o'clock.
As opposed to: "...you get a climb RA"?
No. TCAS is said to be accurate to 15 degrees. The difference between 10 o'clock and 2 o'clock is 120 degrees, more than 30 degrees (= 2 x 15 degrees) which is the resolution necessary to resolve which aircraft is causing the RA.
OK, the aircraft that's going to hit you is at 9 o'clock. You haven't spotted this but you have seen the one at 10 o'clock. You ignore the RA because "you've seen it". Crunch.
Or it is a military aircraft, or a NORDO, or an older bizjet, or a Legacy whose pilots just kicked off the transponder and ATC is giving you a primary return assuming (appropriately) that he is maintaining altitude.
Or it's a cruise missile, a weather balloon, a flying saucer, a flock of birds, etc. Very easy to find edge cases where the system may not work but how realistic are they in a
positive radar environment? If you stray into the path of a UFO during an RA it's just not your day is it? (BTW, NORDO stands for "non-radio"; doesn't mean they're not squawking...)
I am much less convinced than I was about your understanding of TCAS scenarios.
Out of interest (and I'm not trying to "one-up" you or anything), how many real or simulated (as in sat at the controls) TCAS encounters have you experienced?