When on arrival and ATC has kept you high, what will give you the greatest rate of descent: Open Descent or Managed Descent?
What if I reminded you that open descent will provide idle power? Does that help? So... which is the best when you need to get down a little quicker, and why?
While you're contemplating the mystery of the Airbus, I must share a few really cool pictures from Amsterdam.
Next stop: Minneapolis.
Enjoy the Journey!
XO Karlene
What if I reminded you that open descent will provide idle power? Does that help? So... which is the best when you need to get down a little quicker, and why?
While you're contemplating the mystery of the Airbus, I must share a few really cool pictures from Amsterdam.
Next stop: Minneapolis.
Enjoy the Journey!
XO Karlene
If I understand the Airbus (and I probably don't) then Open Descent is like Level Change on the Boeing, and Managed is like VNAV. If I'm right then Open would let you descend faster, and if you needed even more vertical speed you could dial up the target airspeed.
ReplyDeleteI know on the 737 you can also stay in VNAV descent and use Speed Intervene to increase the desired IAS in the descent, resulting in an increase in Vertical Speed. Is there a comparable method on the Bus?
Steve, excellent comment. There is one little catch with the Airbus, different from Boeing. But your comparison is excellent. Look at the photo above. There is a clue in that there picture. I'll be back from the other side of the ocean with more.
DeleteAuto thrust?
DeleteYes... A/T is on, but it's not the solution. Works with both.
Deleteit looks like in the picture that your in managed mode because speed and/or v/s are not shown which let me tell that the MCDU is calculating the best descent based on the rate of economy your entered.
ReplyDeleteTell me if i'm wrong but You can still see the programmed IAS (megenta triangle) but the MCDU as long the engines are throttleling would allow greater speed. It will, of course, remain under the overspeed ribbon
You're close. We are in managed descent as indicated by the green DES. But also notice the thrust is to Idle. Column one. Also... The magenta triangle would be available, and displayed, for Open Descent.
DeleteCan you tell what speed we are flying at?
454 GS
Delete454 GS?
DeleteAmsterdam is a cool place. Everyone is super friendly and everyone speaks perfect English. The houses are tall and skinny because they used to be taxed by the length of their frontage, so owners minimized the frontage length and built high instead.
ReplyDeleteJust don't go into a coffee shop and expect to get a cup o' joe. Actually, as a pilot, don't go into one..... period.
I didn't know that about the taxes and frontage footage. Interesting. Also... some places you can't walk down the street. But everyone is so friendly.
DeleteSo when I am setting up flight simulator for the grand kids, I need for you to do a serious A330 review with me. Your question above is a good topic to start off with as there have been times where I was 90/- miles from an airport and I was called for initial descent. (Sometimes thinking the controllers forgot about my existence.) Mostly on westbound transatlantics where I was cruising 38-41K feet.
ReplyDeleteI always love photos of Amsterdam - thank you for sharing them. Photo journalism is the best!
Have a safe return to the US!
We will definitely go over it. And... 90 miles out at 38-41K, they did forget about you! So sad. We will preview for sure.
DeleteThanks for your comment.
I know your airline operates both the 332 and 333. Are you certified to fly both types?
ReplyDeleteYes, we are certified on both and fly them interchangeably.
DeleteSplit S always works for me...though keeping 1G in the cabin takes some practice. At night in IMC no one ever notices.
ReplyDeleteTim 8DME_W_ORD
Ah... we never have to get to that. Okay... never say never. But this plane comes down really nicely. Especially since we can use flaps, gear, and speedbrakes all at the same time.
DeleteWhich will get you down FASTER? Managed Descent. If you look at the photo above, the speed bug is 300. If we were to use open descent, the power would come to idle, and then plane would fly 300 knots.
ReplyDeleteBut in this case the plane is not flying at 300 knots. The plane is flying just under 320 knots. If you notice there are brackets at 280 and 320. In managed descent the plane can speed up (and slow down as necessary) without resetting the speed within the brackets.
So... in this case, we're above profile. In managed speed the thrust came to idle and the plane pitched over to 319 knots to capture the profile.
Managed speed will enable the plane to descend more rapidly than open descent.
K-
ReplyDeleteNot being a airbus type not sure of the technique you use but do you set a Mach number value in the speed window to descend at or above above aprox FL250 then switch to a IAS when the Mach matches the IAS or is it just knots all the way down?
Tim 8DME W ORD
Oh... we don't set anything in the speed window. We program 330 knots on the descent page and there she flies. Some open the window at 250 (after the plane has already slowed down) But... you don't have to. You can just activate the approach and let her slow down per configuration. This is really an automated plane.
DeleteAs a 20-year Airbus guy (319,320,321,330,340)who arrived on your page via a Google search to clear up some Boeing mysteries as I prep for the B777- I don't really agree with your setup above...
ReplyDeleteManaged speed depends on the Cost Index you've entered. If you have something "normal"- you've probably got a managed descent speed around 270 knots and your upper bracket wouldn't allow you as much room to dive off the altitude.
The more intuitive and expeditious method to get back down on profile is IDLE OPEN, SEL SPD to somewhere around Vmax-10 (and, beware the dreaded overspeed- it's a dumb AP sometimes)- and- if really pressed- throw in a little speed brake.
Now- to learn how Boeing does it!
JetDad, you're going to love the 747... the biggest difference is that you cannot use speed brakes with flaps. You'll have to break that habit!
Delete