We did for about a year or so ,some trials for BCDA for the eurocontrol ,at our home base. Approaching t/d, as computed by the FMC, we asked for descent,and we got clearance ,complete with the STAR.Approaching FL100,we were cleared for the ILS,with no further involvement of the ATC.
All descent was done in VNAV ,and the STAR included some mandatory gates.
Those gates were calculated with a mandatory speed ,and a minimum/maximum FL (altitude).
By doing this trials with different types,at different airports around europe,it was possible to establish the necessary gate dimension ,in order to be able to squeze in it a 737/ 320 and also bigger planes (like 747 ).
All descent was done in VNAV, with engines at idle thrust ,with FMC computed speeds untill FL100, and with gate mandatory speeds bellow FL100. No thrust was required till G/S intercept. We did few hundred flights,and it was ok,we also saved some fuel.
One good thing is less interference from the ATC, also the SID's can also be planned (as a continuous climb..) so they won't interfere with the STAR's at any point. Just imagine different tubes ,not intersecting eachother.
Due to the gates ,it was easy to space very well the aircrafts,and it worked even in very busy airports.Only problem was that the trials were done only by the base airline,so it worked only at off peak hours. But when will become normal practise for every one,my bet is it will work fine.
And just think,at FL 390 to receive clearance :Cleared to descent, Star XXX ,ILS rwy YY...' and at FL100..."cleared ILS YY..." and that's all.
The main problem that rended the BCDA inoperable was weather, when CB existed in the aircraft path,the BCDA was discontinued and the ATC was informed about this.
Also ,in order to get the necessary spacing, the ATC may ask for a specific descent speed from t/d to FL100 ,but the descent was also done in VNAV with idle thrust ,at that required speed.
Bellow FL100 ,the speeds were specified on the BCDA STAR.(the trial ones we had )