Originally Posted by
krismiler
The autothrust is quite slow to react to changes, it probably targeted the lower speed first by reducing power and then realised you wanted to climb so it increased power. It's a 1980s design and can't keep up with even a modern smartphone. You would have been better off waiting until the aircraft was properly established in the climb before winding the speed back or managing it.
Krismiler is correct, in this scenario it will target the speed first, even though the book says it will always give CLB Thrust in OP CLB.
If you just leave the speed were it is, the a/c will raise the nose at max 1G, and the thrust will come on as required to maintain the target speed. Once established in the climb, with CLB thrust set, the desired climb speed can be set.
Alternatively, if you need to start climbing asap, you can EXPEDITE (if fitted), and this will pitch to maintain Green Dot, therefore the thrust will increase sooner. I don't like this for a number of reasons:
The pitch is aggressive for Cabin Crew and pax, and the speed decays very quickly. If you go below your desired Climb speed, it can be a struggle to get the aircraft to pitch down to regain it while continuing the climb.
I have seen folks set a V/S initially too, and increase it as the thrust increases, before OP CLB, it works, but requires a lot more fiddling.
My preferred method, if down low, i.e. 5000ft to FL100 ish, i.e.: On a SID with speed canceled, and expecting a climb soon, keep a bit of a buffer to Vmax, say 15-20kts. (290 works well, and conforms with SID design parameters)
Then:
Set the cleared Altitude,
OP CLB
INCREASE the target speed by 5-10kts. (This will initiate a thrust increase, as the a/c has already pitched for the climb, and you will have CLB THR and OP CLB)
Set desired CLB speed target (I.e: Managed speed or en route climb speed)
It gives a smoother transition to the CLB Thrust, and CLB attitude, also a larger buffer to Vmax, if you hit some bumps.
(NOT TO BE USED IN THE HIGHER FLIGHT LEVELS)
There is many ways to achieve the same thing, but the Airbus works in mysterious ways, this is the way i have found to manage this problem.
Feel free to offer up other solutions.