Ok,
Nice reply, thanks for that.
Idle descent to threshold has been oversold to save fuel, and now lower noise, but it just doesnt work in a multi, or even single variant queue.
I am much more in favor of a controlled descent, especially below 5000 feet. This allows ATC to manage the queue, and tighten up the spacing, if everyone is one the same page. At 3 degree GPA, it is not a whole lot of throttle to go 160 kts.
With a waypoint a speed restriction at 10,000 feet, this provides an adequate 'target' for the box to identify, and pull TOD accordingly. If we need to fix TOD, then idle down to FL10 is still workable, and saves the most fuel.
Other target waypoints at 5000 and 3000 provide the ability to optimize the queue in a multi-variant environment. (the checkride 240 at FL 10 that Boeing has coded in is certainly annoying)
I will be watching the trials of this RNP procedure very closely....