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Therefore I do not see that CDA per-se would have any bearing on this although it is possible that the BA or NATS procedures for flying them at LHR might have some impact.
That wasn't the point I was making. It was that a continuous descent at idle (if that is what occurred in this case)
might have masked the problem whereas a step down to a platform altitude would have required a power-up and so revealed the problem at an earlier point in the approach. The crew would then have had the option of delaying gear/flap which
might have enabled the aircraft to reach the runway.
I fully agree with your point.
If you read my original post I said that CDAs were poorly defined, and that the flavour of CDAs used by LHR were a long final approach intercepting the glide path several thousand feet earlier than normal. I also stated that NATS and BA had agreed procedures that were particular to the approach at LHR.
In this case the procedure was the 160 to 4 as it appears to be known. This does not seem to have been assessed for the risk of a double engine failure to spool up after the slow down from 4 to ~2 miles. In fairness this has not happened before on this approach. However, in safety research a risk greater than '10 to the minus 9' is (supposedly) unacceptable - and that would mean (roughly) something that happens once a second cannot go wrong more than once in 32 years. The acceptance rate of LHR is only around once every 40 seconds at best and the procedure has only been in place around 2 - 3 years (?). So although it is a rare event it may still unacceptable in 'pure' safety terms - but then practice and theory are often different. (Before the anal mathematicians start probability theory on me - I know that probability does not mean it can't happen immediately but that is not the point - it was not considered)
So after all that - NATS and BA may well change the procedures a little - I read in an earlier post that some operators prefer to be stabilized on the approach a lot earlier - I think that this is justified. There comes a time when you have to balance noise nuisance with safety.
However, I do not think that CDAs will go away as the potential financial savings are huge. Research I did for Atlanta showed that savings of 45 flying hours per day were possible. Added to the research from SAS with savings of up to 1000Kg of fuel per approach and the argument for a full CDA is difficult to refute. But late spooling up of engines may be seen as too much risk - and this may result in stabilized approaches from say 5 miles.
This is where safety meets environmental impact (read political problems) - and who knows which way the decision will go?