Yet another PMDG 737 thread......

[zcottovision]

Is it possible to use VNAV descent with the default FS ATC? At the minute I'm using LVL CHG, which sometimes isn't the best.....

[Nexus]

The PMDG FMC and FS ATC are 2 different things and they can't seamlessly

[Silver1SWA]

The FMC can be programmed to begin VNAV descent whenever you wish.  If ATC asks you to descend before the FMC is ready to begin descent, force VNAV to begin descent.

[Nexus]

[quote]The FMC can be programmed to begin VNAV descent whenever you wish.

[zcottovision]

That's pretty much what I was looking for. Now I just have to figure out how to do it!

Also, why the switch to VS below 10,000?

[Nexus]

LVL CHG is so sensitive to speed changes, if you want to lose 10kts, the AFDS will instantly command an agressive nose-up attitude, which sometimes will put you un-necessary high on the vertical path.

If you're noticing that the speed won't drop in V/S mode , simply decrease the V/S and the speed will bleed of..much smoother way of operation, and definetly more comfortable for you and the virtual passengers  ;D

[jrpilot]

I find it so diff. to make a descent with the PMDG 737 becasue I always come in to high...then the VANZ discounects becasue it can't reach the altitude constraints I've asked it to complete

[Nexus]

Junior do the mental math first, are you constraints on the "right" side of the performance envelope, the aircraft must be able to comply with the hard contraints, you know, or else VNAV will disconnect.
Hint: losing altitude and speed at the same time is never easy in the 737.

[jrpilot]

When I descend 90% of the time VNAV will disconnect and I will have to do a 4000 fpm descent. right away...so what are you saying for me to do...descend earlier?...If I use "descend now"   The aircraft only descend at a rate of 1,000 feet per minute...should I use V/S when I use "descend now"...?

[Nexus]

jr, read the post above regarding "DES NOW"
Yes, it will descent with a rate of 1000ft/min, but just UNTIL you reach the original descent path, then VNAV path will follow the vertical profile, as calculated.