P.S. Of the 20 or so pilots that I asked the other day.......not one single pilot requested an econ descent of 270......they were all in the 300-280 range with one exeption who asked for 250 because he was early and the stand wasn't available yet
For a BA A319/320/321 "Econ Descent" is invariably in the ~270KIAS area.
However, this is "best range speed" (adjusted for Cost Index i.e. an element of slightly increased Fuel Comsumption against Time in the air) and is
instantly invalidated if there is to be any holding.
If the aircraft is to hold (and I appreciate it is hard for you to determine), then "Econ speed" is Holding speed throughout the descent. This is "Endurance speed" and we are told the landing order is determined "40 minutes out". The sooner we can be told "there is ~x minutes @ LAM, reduce to Holding Speed if you wish, or when FL150 @ SABER met.." the better
As alluded to above, this is why (some) get a little grumpy when told to accelerate to 280K / 290K / 300K and then to hold. It is very costly in terms of fuel, both £, but as crucially, in "holding time" then remaining available (very roughly, every 2 minutes @ 280K equates to 3 minutes holding i.e. loses a minute of total holding capability/endurance).
I fully appreciate you will get 20 different stories from 20 different pilots... and this is why a consistent line is needed from the airlines
NoD