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.

As was once said by a captain to ORD controller, "the speed brakes are for my mistakes, NOT YOUR's"

Keep it moving....

galaxy flyer, that's an old one.

callinghigh.

Why do you want to know? Are you a controller?

oh

and "TEE CON YES" to a greek boy

There are many ways to lose height and speed, but to lose them at a high rate is generally inefficient. Flying dirty and/or at speeds that differ from your scheduled economy speed is a waste of money. It also gives a pointlessly uncomfortable ride and makes you work a little harder. It's also something that can normally be prevented, if only a bit of thought had been invested by the relevant parties beforehand. At busy airports, ATC generally has a grip on the process but at secondary and tertiary airports too many controllers want to play controller with you. Many also have pathetic "noise" and pointless local procedures. Procedures that require you to fly seven mile finals, rules that prohibit visual approaches, statements of intent regarding CDAs, yet controllers who won't give you a descent.

General numbers: 10 knots per mile and 3 to 4 miles per thousand feet.

But if you are the enemy, how about just letting us get on with it and only interfere if it looks like we are going to bump into something? Or is that a little too controversial?

Ah, the good old days at the old ATH. 18,000 ft downwind, 'clear visual approach and land'.

Such requests are very common in Chinese airspace. One skipper upon hearing such a request rudely responded "I am not a bloody helicopter!" ;)

callinghigh

it really depends on the plane, and the pilot's willingness to make a maximum effort.


exascot, we call that kind of approach a CROWBAR approach.

We use to say we could drop a crowbar out the window (after depressurizing of course) and beat it to the earth.