To give you controllers a better idea of the way we drivers (should) think, consider this:
For planning purposes; below FL200
a) for the A330: 3x FL plus 1 mile for every 10 knots above 170
b) for 777: 3x FL plus 1 mile for every 10 knots above 190
Using GS instead of TAS gives you some credit for wind; to make it more accurate try adding 1-2 miles for 10 knots tailwind @ FL200
Not perfect, but it should give you a ballpark figure.
Without any doubt, the A330 is harder to decelerate - with flaps in or out -and Emirates management have drilled a scare of unstabilised approaches into crews. At the same time, 777 speedbrakes are more efficient than those on the A330, which makes A330 crews even more cautious.
In any case, putting an A330 on the GS with 170 knots (or 180 with more flaps/drag) and a 777 with 180 should keep drivers out of trouble.
And I couldn't care less about the "my airplane is better than yours" idiocy or whether this is to "superior airfoil design" on the A330, or "superior handling qualities" on the 777. We are unlikely to change the way our particular airplanes behave and we might as well get used to it.
Another part of the problem could be varying descent speeds.
It used to be 300 (previously 310) knots on the A330 and 310 knots on the 777. As management tries to reduce fuel consumption, we descent with cost indices that can drop descent speeds down to 270 knots, or below. (If this continues, some guys may well have to accelerate to 250 KIAS when descending below 10,000.
) The next guy says "hell, stuff this" and descends at 310 as before.
At one stage, I tried to get management interested in using a standard descend speed of let's say 290 knots (for the sake of fuel economy) for all fleets.
That would have made us more predictable for ATC who would no longer have to increase the speed of slow traffic (means more fuel burn) or reduce the speed of the faster traffic (means more fuel burn, since they extended the cruise portion beyond the point where they could have descended at a lower speed), but management never got the picture and the proposal must have gone straight to file 13, because I never even got an acknowledgement.
Interesting to note that you controllers put altitude into the equation and consider the fact that 300 KIAS @ FL200 moves us a lot faster across your screen than 300 KIAS at FL100. It must be literally part of the way each of us sees the picture and applies mental arithmetic. You see a blip moving across the screen at the same 300 knots, but different altitudes and rates; while we pilots work on FL X 3 plus whatever to figure out required track miles.
Great talking to you, gents.