alright, alright. yes, I became a FBW 320  f a n b o y and lost some 737 capabilities having not flown the 737 for quite a decade. so don't shout at me like manny may do but help me how to engage descent once I reset MCP from say 35000 to 18000 feet and I am past the TOD already (so I forgot to reset the MCP in the first place). in the neo I click the dial but not in the 737, at least with the honeywell AP. so far I just dis- and reengage VNAV but I would expect there is a more - well - professional way? quick answers please as this potentially embarrassing post will destroy itself after some 20 years or so

Edited May 11, 20224 yr by DAD

I'm trying to figure out the same and a search of some forums has given a variety of different ways of doing it. Some say to use level change, others VS or cycle VNAV.

A useful feature of the 737 is that the in-flight save from the sim menu actually correctly saves and restores the complete aircraft state unlike the FBW so you can actually save a scenario where you're close to TOD and experiment with different methods.

Reset the MCP altitude to the desired constraint altitude (while still in VNAV) and click the ALT INTV button. That will start the plane back down. 

9 minutes ago, Bdub22 said:

Reset the MCP altitude to the desired constraint altitude (while still in VNAV) and click the ALT INTV button. That will start the plane back down. 

alright, thanks. did not find that button first until I realized that I use the COLLINS and not the honeywell, honeywell has that button, collins does not

55 minutes ago, Bdub22 said:

and click the ALT INTV button

just enroute LFKB - LEIB and that works like a charme. Thanks for pointing this out

Both MCPs should have the Alt Intervention button... or, well, let me rephrase that: both of them CAN.  We have both MCPs in my fleet and they both have the Alt Intervention button... but that doesn't mean that the Honeywell MCP that PMDG modeled does. My tests so far have only been with the Collins.

That button does hide a bit on the Honeywell panel though... might be worth another look. 

Interestingly, the VNAV ALT is a mode I'd never seen before trying the PMDG... our fleet doesn't do that at all.  In cases where the PMDG drops into VNAV ALT, our planes just revert to Alt Hold.  So to start down again, you reset the MCP altitude and reselect VNAV.  It's interesting to learn how many variables there are in 73s all over the world. 

Edited May 11, 20224 yr by Stearmandriver

Pretty sure both panels have the button. You can also use "Descend Now" in the Decent page in the FMS.

Honeywell

 

Collins

Edited May 11, 20224 yr by Zangoose

I'm assuming the Collins MCP is more modern and easier to use than the Honeywell?

15 minutes ago, Zangoose said:

Collins

alright, wondering why I did not find that button then, maybe hidden from my viewpoint, will check on next flight

33 minutes ago, andreh said:

Pretty sure both panels have the button. You can also use "Descend Now" in the Decent page in the FMS.

I think Descent Now only works when you descent BEFORE the TOD? That said I never tried it after the TOD...

When you pass tod , plane descent himself if you change altitude before, intv is only if you have a step climb or descent. And you can use descent now on fms if controller ask you to descent early.

25 minutes ago, captain420 said:

I'm assuming the Collins MCP is more modern and easier to use than the Honeywell?

Collins is the newer one - History of the various MCPs the different 737s have had over the years - http://www.b737.org.uk/glareshield.htm

2000 hrs 737 says:

1.  Use 'Descend Now' around 10 miles before DP (dependent on wind) to ease the aircraft into the descent at 1000fpm.

2. If descent clearance has been given and set, aircraft will start descent at the DP (with VNAV engaged).

3. Missed the DP and haven't set a lower level: Set lower level, LVL CHG and Speedbrake to regain the descent profile. VNAV in real life is far from perfect and 'Drag Required' will often display.

Edited May 11, 20224 yr by ArkRoyal

What is DP?