Can I add my two pennorth, some of which has already been mentioned.
I am constantly surprised by pilots talking about the 'kill zone' and over stressing aircraft to 'escape' and thinking they are about to 'die', as if they are driving along a motorway and suddenly see a car coming towards them in the opposite direction. Nothing could be further from the truth.
Your TCAS is constantly interrogating all the aircraft around it, (can't remember how many, but it is dozens), and assessing them all for threats. It will give warnings (TAs) if it sees proximate traffic, and avoidance advice (RAs) if a conflict is predicted.
TCAS units all talk to each other. If an RA is required the two aircraft's TCAS units will talk to each other and agree a plan. One will decide to go up, the other down. One makes the final decision, and they both agree which one will be the master according to which one has the lowest squawk code. (If one aircraft cannot react properly, for example if it is on one engine, the other aircraft will double its avoidance if necessary. This is why you select TA only on your TCAS if you've had engine failure.)
TCAS will issue an RA to its pilots with 30 seconds to the predicted conflict. Look at your watch now and watch the second hand for 30 seconds. It's a loooong time! All that is needed therefore is a GENTLE climb, or descent, or maintain what you are doing, and the aircraft will pass harmlessly.
If some idiot decides to 'haul on the controls' they might well put themselves into conflict with other traffic above or below them, which might trigger further RAs and massively complicate what should have been a very gentle and controlled manoeuver. If some idiot decides to ignore both TCAS computers and make up their own avoidance or do the opposite of what they are told, then both units will recalculate their avoidance plan and this is where changes of instruction come from.
To sum up,
-Nobody is within milliseconds of crashing when a TCAS RA is issued.
-All that is needed is a gentle change of vertical speed - sometimes not even that, just maintain the vertical speed you are doing.
-Always obey TCAS RAs, do NOT do your own thing - do not make decisions based on what you might see out of the window. You don't know if the aircraft you can see is the conflict aircraft, and if you choose the 'wrong' aircraft you might do the wrong thing. Remember, the TCAS units are talking to all the other TCAS units around you, most of which you cannot see. TCAS will 'see' a conflict aircraft at least a minute before you will.
- don't panic - as long as you start to do what the TCAS IVSI display tells you within 2.5 seconds, (and you will be prepared to react already because you will have been warned by the TA), there will be absolutely NO drama whatsoever.
- there is no need to haul on the controls, the TCAS will give you warning with plenty of time for you to react safely and gently.
Last edited by Uplinker; 27th February 2014 at 06:23.