Spooling up

[nsproles]

Before take off, the engines of the Asobo A320neo are spooled up  to settle on 50% N1.  If all is OK, the throttle is moved to flex and the  take off is effected.  However, is the spooling up to 50% done while moving along the runway or are the brakes applied and then only released once it is shown that the engines are running satisfactorily?

[nsproles]

I am now able to answer my own question.  My problem was that with the default A320, you have to look down at the throttle quadrant in order to properly set the throttle at Flex for take-off.  This means that you could be wandering off centre line before you look back up again.  That is why I was wondering if holding the brakes until you set Flex was the way to go.  However, I have been using the FBW A32NX and with it there is a clearly audible 'click' as you push the throttles through their detentes.  There is no need to look, you only need to listen.  This means that you can throttle up to Flex, once you have confirmed that the engines have settled at 50% N1, just by counting the 'clicks' as the throttles pass through their detentes.  The clincher is that the FBW manual states that brakes are released once the engines have spooled up satisfactorily, and that the aircraft is allowed to accelerate as the throttles are moved to Flex (or TOGA if that is necessary).