I am a little confused in setting up my descent in the A320. In the PMDG 737 you reduce the altitude on the FMC. When the plane reaches the descent point in the flight plan, it begins descending to the altitude you have preset. Does the A320 do the same? It seems when I roll down to the lower altitude, whether I press it or pull the nob, it begins to descend immediately. I am sure I am missing a step. Any help would be appreciated.
The airbus does not auto descend, it works different than Boeing.
Yes, the FBW A320 will do an auto descent from the Top of Descent.
Airbus philosophy is pull a knob toward you, you have control.
Push it, the MCDU controls the aircraft.
The throttles must be in the “Climb” position at all times in the flight after being prompted at the climb altitude, only being moved at the “Retard” signal during landing.
In this case, you would dial in the new altitude, and push (left click) the Alt knob to allow the A/P to manage the descent (same for a climb) of the aircraft on the correct MCDU profile from the T of D.
Pulling it toward you (right click) allows the Airbus go into “open” descent (or climb), and the aircraft will maintain the selected airspeed you have chosen, and descend as fast as it can at that speed.
This philosophy works for all A/P buttons on an Airbus A320 and its family.
but it’s not an auto descend in the way a Boeing works. You still have to configure both planes for descent to some degree but the difference is you still have to tell the airbus MCDU that you would like to descend at the moment you would like to descend by pulling the altitude knob on the MCP. A Boeing assumes you’d like to descend based on the VNAV path calculated by the FMC (through your flight plan data) and any deviation requires pilot intervention be it heading, speed or altitude; you only need to configure the bottom altitude you’d like to be at and the plane will adjust the descent path accordingly. Simply put: They are different forms of automation requiring different levels of intervention based on the procedure you’d like to accomplish.
Any airbus simmer i’ve met who’s tried a Boeing plane typically says something about how nice it is they don’t have to pull any buttons to descend.
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Thank you for your clear reply (also to the poster below.) One problem I seem to be having is setting the descent arrow on the flight path display. I follow the steps of setting up the descent, but the arrow never appears. What step have I missed?
If you have filled out the INIT, PERF, and F-PLN pages correctly, then make sure there are no discontinuities in the plan.
This may be some help as well, it is a link to a vid on how to set up FBW’s MCDU:
Been having problems with the A32NX since the new FMS update. I could previously perform a VNAV descent as you stated in your post, but since the update the plave flies right through the T/D point and I have to do the descent using Open Descent and/or V/S. Seems like the VNAV is broken…
How the A320 works:
When you have select a lower altitude and PUSH the Alt button BEFORE TOD the plane starts immediately a descent at 1000 ft/min.
It will keep it until it intercepts the computed flight path.
On Navigation Display a blue ray shaped arrow show where the intercepts occur.
Then it returns to the maximum descent rate keeping the computed speed. It will normally go to Idle but will change if needed to keep the speed.
The A320 FBW and Fenix implements this.
The A320 also but no blue arrow.
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Pressed reply to soon on previous reply:
The A320 V2 implements correctly the descent profile BUT does not display the Blue arrow which confusing because the pilot does not know on which phase it is.
However the Green Dot on the altitude indicator works and tells us when on, above or below the profile the plane is.
However the MCDU on the V2 “sometimes” gets all calculations wrong (not often) and T/C, TOD, fuel predictions… are absolutely wrong!!! But some other parameters we input are correctly taken into account.
I have not yet found a way to reproduce these errors consistently. They are rare and apparently random.
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