Originally Posted by
sonicbum
Hi,
First off all congratulations for having successfully completed your line training! A little less congratulations for your trainers that have left you with those unanswered questions
Let's look at a basic but effective descent management tool.
The good old Altitude x 3 to start with.
Then adjust the wind -> +/- 10% tail/head winds
Then adjust the speed + 1 NM for every 10 kt above 200 kt which is usually somewhere around Gdot.
Finally the weight adjustment. On the narrow body Airbus I don't bother too much; if I am very light I will probably need to reduce the RoD at some stage and if I am close to Max Landing Weight I might need to use some speed brakes.
So You need to start your descent from FL350 down to your platform of, let's say, 3000 ft.
32 x 3 = 96 NM
20 kt tailwind = +2 NM
Deceleration = 7 NM (descending at 270 kt)
Start descent in OP DES around 105 NM.
From there keep calculating and adjust, every 5000 feet or so. If you do have STAR constraints to meet in the middle you will need to set targets for the different constraints.
Generally speaking this sort of technique of descending in OP DES/VS works well to optimize fuel consumption when there are not too many constraints to be considered.
It is a "homemade" version of the Descent Profile Optimization by Airbus and can lead to some savings if applied correctly.
Thank you very much!
Unfortunately during training I see some captains are not really able to transmit those things, on energy management sometimes they just rely on experience and feeling in order to judge descent and configuration, which is obviously perfect and normal after many hours, but for a fresh new pilot cadet level some rules of thumb and guidance are still required, as experienced needs to be built…
Thank you for your help, I’ll try. Sometimes I get a common restriction with 9000/29 nm before joining an arc dme and descending on the arc. I reduce to speed 210 and then maintain this speed in order to avoid overshooting. When descending gradually I see losing miles (especially with 10kts tailwind), I try to solve going F1 speed 210 and sbrake but it’s not really efficient and couple of times had to use the gear… Not nice that feeling of rush thinking “will I make it or not”
Probably also the plane makes the difference… some of them look very reluctant to descend steep
Thanks again for the help.