Hi All,
I am struggling to get my decent rate with FBW.
I am using the auto calculate in the tablet On my FMC my descent speed is set to 250kts.
The tablet tells me to decent 72NM before destination at 3 degrees.
My cruising ALT is FL260 and my ground speed is 570.
Will FBW automatically calculate everything for me so if i descent from 72NM i will arrive there at the correct hight? Or do i need to manually input my VS
normally i just set the target altitude and push the knob once at the TOD.
…best is to just look up 320simpilot on youtube. everything you need to know, he’s got you covered.
if you use the percentage of VS of 3°, you have to put that manually in your VS of the autopilot.
Personally, i use a descend rate of 2000ft/min for the pax comfort, and give me some buffer “zone/time” to dive slightly more ( still thinking of pax comfort ) in order to correct if needed.
if you switch On, the constraints/restriction of ALT and SPD, whil starting the STAR, and switch your descend ( and SPD) mode in computed, and not open, you can always put the ALT required for the 2nd next waypoint, and the autopilot will always respect the ALT and SPD constraints, untill the next waypoint is passed
Moved to #third-party-addon-discussion:aircraft which is more appropriate 
If you use the Open descent mode it will give you an accurate but variable descend rate and you will match you altitude when you use the calculated FMS TOD.
If you’re using VS or FPA you just need to think about your groundspeed which normally drop during your descend and that means you have to correct the VS/FPA or, as already written here, you have to start your descend earlier.
Maybe not the correct way, but I’m not a pilot so far.
I use an android app called “descent calculator” by Luis Alvarez.
I enter current Altitude - target Altitude - Ground Speed and the Descent Rate ( feet I want decent at ). It then gives me the Total Descent - the distance in miles and the Time the Descent will take.
I found it verry helpful so far.
You can also switch to FPA/TRK mode, and set your FPA to -3°. And the aircraft will automatically control the speed and V/S to maintain that 3° descent. If you time it at the right place, you’ll end up at the right place at the right time for final approach.
The default ATC doesn’t use the same calculation though, so if you’re using this method and also using the default ATC, they’ll get upset.
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