Speed reduction and descent
It is known that it is not compatible to ask a pilot to reduce speed and at the same time maintain a high rate of descent since it requires the plane to temporarily level off or keep a very low rate of descent and then continue descending.
-Can't this be achieved with speed brakes while in descent without leveling off? And how many miles are needed to reduce speed e.g. for an A320 from 290 to 260 KIAS?
-What is the relationship between a high rate of descent and the aircraft's speed? (e.g.is a B747 descending with 300 KIAS able to give more than 2000-2500 ft/min without using speed brakes? And what about the speed then?)
-Is it better to slow down an aircraft early in cruise flight if needed than restricting him in speed during descent? (If reducing e.g. a B738 to 250 KIAS in descent what is the best rate of descent he can give?)
Please give an example with numbers to make the above clear.