Not actually. A CDA assumes a continuous descent, all the way through the initial maneuver for the approach...say passing LAM on the 265 heading, downwind for 09L. The director gives you 'track miles' to run, I confirm that with my FMS progress page. Having done that, have a look at my altitude and do some quick math, to determine if I'm going to be high or low on the slope intercept. The trick is to continue a nice, uninterrupted descent all the way through and intercept the localizer AND glideslope at the same time, without having to level off. Its efficent, economical and comfortable.
My question had been to query if the controllers actually wanted me AT 3000, THEN cleared for the approach. But it appears that my initial understanding is correct..which is continue with the CDA, but if the controller needed me at 3000 or 2500, THEN intercept, I would be so cleared to do so.
We can have all the fancy vertical path information, etc, but nothing beats using 3:1 on track miles to run and keep a running computation with the DME and progress page. Then, adjust the descent rate using V/S or speed brakes. One also has to comply with speed restrictions coming around the corner as well.
When it works out its a lot of fun and kind of breaks the monotony of fully automatic approaches and hustling down to an intercept altitiude and dragging the airplane in, on final approach. When it doesn't, it gives cause to think how to do it better next time!
...mind games in airplanes
