Farmer - I think I get the jist of what you are asking. You want to know why someone would call for LVL change after having selected N1 during the climb out because according to your understanding of the AFDS, You can simply just wind up the speed and it will follow the speed anyway (without pressing LVL change).
Exactly.....why didn't I just say that?
But I am still wondering because
So by just winding the speed selector up at your acceleration altittude and not selecting LVL CHG the aircraft will accelerate to the new MCP SPD PLUS 20kts (ie the pitch mode of the FD will still remain in TO MODE).
is not correct, at least not in the a/c I fly, they happily pitch to the speed selected in the window.....all the way up into flight levels if you don't select anything else, and the whole time the FMA displays N1 in the a/t box and TOGA in the pitch box.
So.....why do they do it? There will be a reason I'm sure. I am not doubting it's the normal or maybe even best thing to do.......I just can't see the point in it and I wouldn't mind knowing.
thanks again for the answers.