themwasthe days
I think that I see what you are getting at. You are looking to design a procedure for arriving aircraft which is both efficient and minimises environmental impact. Since some respondants have opined that a level segment is not always a bad thing - a CDA might not be what you are after!!
If you turned up at my door today and asked my opinion, I would say that since you are trying to achieve an awful lot from one procedure, the CDA is the way ahead and that in my experience Heathrow and Gatwick (at least a couple of years ago) set the gold standard.
ATC Aspects
The STARs seem to offer an idle descent whilst operating at "normal" speeds. The ATC procedures (agreed levels etc) allow the descent to be continuous under most circumstances.
The radar vectoring by LL DIR follows a path which is fairly predictable to regular visitors. The speed control they use 220/210, 180, 160 seems to fit well with the majority of types operated into the airport. London TMA airports are the only places where the pilots are always given a very good idea of the number of miles to run - this is the key factor in achieving the CDA.
Flight Deck Aspects
I really would not get too worried or bogged down in FMS operation, autopilot mode etc. I think I have probably flown various parts of the approach in every possible mode.
With the sensible profiles that have been chosen for Heathrow when a continuous descent from cruise starts to become impossible because of holding, it is often still possible to keep the thrust at idle and slow down a bit each time the aircraft levels.
Drawbacks and Areas for Improvement
- A level of holding is required to maximise runway utilisation and this occurs at low level which is inefficiet in fuel. If you were starting again it might be worth trying to hold a few more miles out and higher up.
- The lateral track around which we are vectored is known only to regular visitors. I would publish a nice glossy briefing showing the tracks typically followed with reference to waypoints held by the FMS (eg LON, LCY, WOD, KILBA etc). Some pilots actually draw a "route" in the FMC based on what they have flown before and referenced to navaids (eg BIG270/10 etc). I would publish a typical set of these in the brouchure.
-Slightly off topic but, I would have the tower ATSA call TC SW ATSA every time something of operational importance is added to the arrival ATIS (eg "severe icing FL80 at LAM" or "moderate turbulence below FL100 at OCK"). The ATSA could then tell the traffic manager, who could chinagraph it on to that laminated sheet which tells the TMA controller the average delay. At least then we pilots would not think that the TMA controller is trying to kill us when he/she clears us to a level at which to hold that the ATIS says is nasty!!
Just my thoughts
G W-H