Gatbusdriver,
A CDA is not a descent in idle, it is a continuous descent (min I believe is 500fpm) with an allowable level segment (without checking think it is 2 mile i'm sure someone will correct me).
Therefore once you are established on the glide most people will only be at approach idle to get the speed back after 4 miles, where you have invariably been maintaining 160kts.
Ergo I think CDA's have little bearing on this incident.
Thanks, but I know that. I have seen
plenty CDAs which
do result in a descent at idle to inside four miles, especially at LHR where the controllers will cut you in short if there is an opportunity for them to do so - just as they do at LGW. That's why I posed the original question.