If Boeing and Airbus philosophy are the same here (I suspect that they are) that CI = 0 = Minimum fuel for the sector, then the scheduled speed for climb will be slightly above that for the best rate, and, for practical purposes, the best rate.
Best Rate climb speed in isolation offers good fuel use per mile, but by surrendering just a little bit of Rate of climb by flying at a higher speed, more ground miles are covered for almost the same fuel burned during the climb, thus eliminating the short incremental cruise that would otherwise have been needed if climb was at exactly the best rate, thus decreasing sector fuel used. (You lose a little of one, you gain a lot of the other).
CI = 0 on descent is a different matter altogether, where the scheduled speed is quite close to Vmd, a much lower than normal descent speed. The object here is to minimise rate of descent whilst still at a 'respectable' speed, and making the most of the very low fuel flows at idle thrust.
Regards,
Old Smokey (Who now types double space because the new format eliminates the single space)
