FMC .. Reset

[airliner_75 0]

Hello,I know it is a newbie question. I searched for the answer and I could not find it. I couldnt find it either in the mauals. It maybe is written but not clearly.I searched on other forums and I think I found the answer but the procedure is described differently and different buttons are called differently so I do not know what is proper procedure.I just want an anwer to one simple question.when descending some 40nm from the Top of the Descent I press the DES NOW on the FMC. Now, my question is if someone can really help me with how do I reset the MCP Altitude. Is it done only by selecting a lower Altitude, is it done by pressing the ALT INV button which is described in some other forum, (is the ALT INV button , the little one even functional?).How do I do that?Thanx all in advance.Kind regards/Artur

[downscc 1,327]

I assume you mean 40nm before TOD. You need to put your "descend to" altitude in the MCP then press DES NOW. She will start a 1000 fpm descent until reaching the VNAV PTH then resume the programmed descent profile. I've never found a use for the ALT INV button, but my flight experience is limited to US short haul routes in the B737. I prefer to descend without VNAV, instead using speed and VS to manage the letdown because the FMC does a poor job of handling altitude constraints.