CDA's
Hi Guys, just read the post and thought i'd throw my pennys worth inot the mix.
I have been on the 757 for about 18 months now and can say that having done some serious line training before being let loose on the real world so to speak, I must have been told about 40 different ways of doing a CDA.
However the way that works for me is to use the FMC and VNAV down to about 15000' and then go for FL CH and V/S to fine tune everything, especially as like you say above ATC start vectoring you about the place, VNAV becomes more of a hinderance.
That said though, if you do get the chance one late evening and get direct to the centre fix of wherever from about 300nm try and let VNAV do its bit, it is pretty good when it works in a straight line and you get a descent clearance right the way down without levelling off etc...
One more note though...how good is it when ATC ask you to maintain 320kts minimum, its FL CH all the way down, and just following the barbers pole up the ASI
Fly Safe..