Hello there, My first post here and I can't wait you answer this one.


Page 37 of the "B757 PART II – Aircraft Systems" manual I can read:

7. Speed Knob:

... "When VNAV is engaged, pushing the speed knob transfers control of the aircraft speed to the FMS from the speed knob. A subsequent push transfers the speed control from the speed knob to the FMS... Manual speed selection (speed intervene) does not disengage VNAV...

No matter how I click on this knob: right click, left click, 2D, 3D panel I can't "push" the knob in order to engage manual speed selection and left VNAV engaged. It react as if I wanted to twist the knob, as if there were no sensitive area.

So my questions are:

Is the manual wrong and there's no manual speed selection mode while VNAV is active ?

Am I clicking the wrong way ? What would be the good way to click the knob ?

Thanks for helping