How about using Speed Invervention?

Push (when VNAV engaged) –• IAS/MACH display alternately shows selected IAS/Mach and blanks• when IAS/MACH display is unblanked, FMC speed intervention isactive, FMC target speed is displayed, and IAS/MACH Selector may be used to set desired speed• when IAS/MACH display is blank, FMC computed target speed is activeand displayed on the airspeed indicator.

FCOM2 - 4.10.4

I am no expert, but if you go through your legs starting from the end and apply the 4x rule to check if each of your waypoints is low enough, you should have plenty of space to slow down. For example, if a waypoint 12 miles from the airport says "/5000A", it is clear that you are probably going to overshoot, and you should change it to r "/3000B", and maybe put a lower speed if necessary . If you want to be realistic and consider this "cheating", you can always try sticking your hand out the window to increase drag... Henri

In DES NOW VNAV goes in under-the-path mode. I.e. FMC SPD and -1000 fpm vertical speed until crossing the path OR if it transitions to approach phase level off until crossing the path. When on path (or to be precise near the path) VNAV will resume normally.

How about using Speed Invervention? FCOM2 - 4.10.4

Speed intervention is only available for the Des when the Des page is active (Actually being in the DES flight phase). So, it is after the fact. I would like to plan for a speed target des while in cruise phase and have the FMC calculate and forcast the new TOD, ETA and path based on a changed speed durring the Des portion of the flight. The FCOM section 11 describes the ability to command manual speeds either in Mach or in CAS for a Vnav Manual Econ or Manual Speed descent before des is active.

In DES NOW VNAV goes in under-the-path mode. I.e. FMC SPD and -1000 fpm vertical speed until crossing the path OR if it transitions to approach phase level off until crossing the path. When on path (or to be precise near the path) VNAV will resume normally.

Thanks for detailed reply, EMV but..It is a normal DES phase most of us usually use but if pushing DES NOW makes VNAV to DES VNAV SPD mode, (not PTH)as described on FCOM2, "DES NOW (VNAV SPD) does not attempt to capture the VNAV descent path."This means as long as I descent fast enough, there'll be no chance to meet calculated descent path.So, the question is.. which mode should be used to get back to the predicted path and eventually see VNAV PTH on PFD. p.s. Actually this is so little part of the flight but we all wanna do that all with FS world.. right?

When you press DES NOW it goes to under-the-path mode and DES phase becomes active prematurely. What may happen however is that the active wind and temperature mixing model starts working, in which case you are actually over-the-path due to unforecasted tail winds or very large ISA deviations. The other thing is that you might be exceeding the FMC absolute limit speed for DES which is the lowest of 330 / M0.80...In this case VNAN goes into overspeed mode (i.e. VNAV SPD). (I hope we are not confusing DES NOW with resolving VNAV ALT with ALT INTV here...)

Speed intervention is only available for the Des when the Des page is active (Actually being in the DES flight phase). So, it is after the fact. I would like to plan for a speed target des while in cruise phase and have the FMC calculate and forcast the new TOD, ETA and path based on a changed speed durring the Des portion of the flight. The FCOM section 11 describes the ability to command manual speeds either in Mach or in CAS for a Vnav Manual Econ or Manual Speed descent before des is active.

You should definitely be able to define your own speeds. Are you using the correct entry format? Are you overwriting the default with your own descent speeds? Eg. .78/280? Remember that the FMC is going to switch from Mach to IAS when they meet on the way down (around FL260 or so). Most crossing restrictions are below the altitude where you'd have IAS restrictions instead of a Mach restriction. Eg. Cross NORMY at or below 13,000, 270 knots.

I just did another flight and this time instead of trying to enter the Mach number, I entered the CAS for that Mach number at given alt and it worked. For some reason the Des page pre des will only accept CAS as target speeds instead of Mach numbers. I'm gonna take a stab at this and say, it's because every CDP has to be for a constant airspeed and not a Mach number or else the CDP would not be a CDP and the descent path would get steeper at lower altitudes since if you targeted a mach number, your airspeed would increase as you started to descend. This makes sense, since the FMC in cruise, will try to predict a T/D based on the numbers in the DES page only on a Constant Descent Path... Wish it was clearer in the FCOM JB

As long as you put them both it, It should work for Mach and IAS. Have you tried putting both in? .78/280

I have not, loading up FS and will give it a try... Thanks JB