Flight directors and speed coupling on A320 and 737

[737Andi]

Hi,

I noticed that the flight director bars on the 737 are coupled to the speed knob on the mcp while the flight director bars of the A320 are not coupled to the speed knob of the FCU.
To make it clearer what I mean. If I change the speed to higher speeds in the 737 the FD bars are going down (nose poiting down to gain speed). In the A320 the same action is not moving the horizontal FD bar.

Hopefully my question is understandable.

Thank you!

[Tail-take-off]

It depends on the modes being used and how they interact with each other. The simplest way to explain A320 pitch behaviour is to think about the auto thrust modes which will either be a fixed thrust (idle, climb thrust, MCT, TOGA) or variable (speed mode).

Speed mode is basically associated with flying a constant profile like maintaining an altitude or given vertical speed. In such modes pitch is adjusted to fly the profile. If you select a higher speed thrust will increase. Obviously as you fly faster the pitch required to maintain the profile will reduce but the initial response is purely thrust.

In fixed thrust mode pitch controls speed. If you increase the speed demand in an idle descent the nose will be lowered.

I hope that helps.

[deltahotel]

Hi Andi. Are you using the MCP SPD to change thrust via the AT or to change speed with pitch (climb or descend)?