Ian W , I do not intend to start another debate with you , you are right in theory of course, but just for the sake of informing the others "normal" people dealing with day to day operations . 4D Trajectory based ATC is a very promising concept but unfortunately long way out. My guess is at least 20 years , if not at all because superseded by another technology .The 2 main blocking issues of the 4D trajectory based ATC, are the implementation of a global ( preferably unique ) data link which is both fast and able to absorb heavy data exchange . This does not exists yet . They are ideas how to solve it but will take a decade or so to be standardized ,. The next issue will be aircraft retrofit. Airlines are furiously against retrofit and as long as you will have multi mode operations and the sacro saint " first comes first serve " rule, there will be no real financial benefits and no incentive for the airlines to equip and implement. The same old story . Talk to the ATA in the US.
BTW ,you mention earlier of using ACAS as mitigation . I know the US is pushing for that but no chance for this in ICAO land, and in Europe. ACAS is a last minute safety device , not a separation tool . Plus ACAS X will fall into the same issues due lack of an adequate Data Link .
Gusting 45 :
I for one, will always feel happier to know that responsibility for the safe conduct of my flight and it’s control is under positive management of a human and that the responsibility has not been offloaded on to someone who has no skin in the operation
Rest assured that it will be like this. in ATC at least . Full Automatic ATC has been demonstrated not to be improving capacity, in fact the opposite is true, and even more so in TMA/ APP /. It might change as new technology comes along,of course, but not in our lifetimes. I would say ..