Many times I try the CDA but ATC bugger it up!!
Try doing a CDA into London City when you have to be at FL80 by sandy which is a lot more than 24nm from touchdown.
Probably not a great example but going into Luton from the NW, trying to hit the Clippy level spot on only to get an early left and not via the lorel but a descent onto downwind for a tight base.
We need to know early.........and the lack on info often results in a ;
"if we descend early we may get a tight base" or "if we are lower they tend to giver a shortcut" or" this vector is taking us away, let's expedite down and perhaps get a better vector".
One aircraft I fly can not fly clean down the glide at 160 knots. Therefore we hang out eh gear. Unfortunately, the gear provides a little too much drag so we insrease the power.
The lack of aircraft type and poerformance knowledge problem identified over a decade ago has simply gotten worse overall.
Regards,
DFC