PPRuNe Forums - View Single Post - A320/A321 energy management and configuration
Old 31st May 2023, 06:42
  #9 (permalink)  
sonicbum
 
Join Date: Mar 2012
Location: Having a margarita on the beach
Posts: 2,427
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by FM_A320
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.
No worries.

Next time take your 9000 ft as your aiming point and calculate from there. You should end up there with Gdot ready for your arc.

To crosscheck how you are doing during descent also use the "official" Airbus formula:
Required Dist to descend = Diff. in FL / FPA
I.e. I am passing FL250 descending FL90 or 9000 ft like in your case so that's a Delta of 160 divided by what the bird shows, let's say 4° probably -> 40NM needed bare minimum distance. That's where all the psychometrics pain in the a°rs math tests come in handy

You can monitor you current FPA in Descent by occasionally going bird ON and see how you are doing.

As a general rule try to correct your descent profile while still far from the target as you will have many more tools, such as increasing your IAS and using speedbrakes. This combination can double your descent gradient when you're still far out and can afford higher rates of descent and speeds.
Below FL100 you will mostly be on a 3° descent on idle thrust, that you can increase by adding speed brakes and bring it up to even 7° by going full manual speed brakes at 250 kt but there are some threats involved in doing that (high rate of descent below FL100, manual flying with tunnel vision). So I would recommend to keep your AP on and accept the half speed brake of the A320.

During your next flight go Bird ON from time to time during descent and see how the aircraft behaves at different levels, how air density variations and wind changes affect your descent gradient. That should help
sonicbum is offline