Originally Posted by
OPEN DES
1. A tutorial is not a controlled document, latest one is Dec 2019.
After initial (common) actions:
SPEED Pull & Set GD
if appropriate:
HDG Pull & set
.....
ALT set & pull
In fact the order of actions in the tutorial is different from the FCTM, FCTM is king.
2. The FCTM mentions:
When ready for descent, the PF:
-sets the SPEED and pulls
-sets the engine out recovery altitude and pulls to engage for OPEN DES
I say again:
If you PULL altitude before approaching green dot (spd trend is a good guide) the aircraft may descend earlier than AT green dot. I.e.: level flight is not guaranteed due energy exchange ratio between speed and altitude.
If You pull to engage OP DES before the the speed reaches green dot the aircraft MAY start a very shallow descent (50-100 ft/min?) which is absolutely no problem and is considered by Airbus in the design of the procedure. On the other hand if You reduce speed below GDOT by pulling ALT "exactly" when Your speed index is at GDOT then you MAY slow down below GDOT which in single engine at high altitude is a big no no no.
For the SAME reason we don’t PULL ALT in the EFATO profile, before green dot is reached. (Trend touching index, sic!)
cheers
When the speed trend reaches green dot vs green dot is reached is DIFFERENT. A speed trend is a TREND : your actual speed will be lower.