I understand 1)entries and execution in the FMC and the need to have the commands become BIG 2) inherent conflicts with speed and altitude changes 3) how to fly the aircraft with MCP commands only 4) the need to dial in altitudes on the MCP.I am having problems with speed/altitude constraints from the FMC. Using Mr. Metzinger

At the Top of Descent point, nothing happens. You need to have a valid E/D point for a PATH to be calculated by the FMC. You already reset the MCP to 7000 prior to TOD but this statement "So, I push VNAV and the aircraft descends busting through the 12000" makes me wonder IF you were in VNAV at TOD? Why would you have to push VNAV again if you were really in VNAV to begin with?To paraphrase his suggestions, LBV should be 284/12000 If you ask me (I have not seen his tutorial) this 284/12000 should NOT be a restriction because that speed looks like a descent profile speed not a restriction for an approach. Plus why would anyone want a speed restriction above 10000' if it is not required? You must understand the proper operations for various descent modes. In the default PATH descent mode the aircraft is keeping the path not the target descent speeds. If you had a real restriction at 12000' why was the MCP set for 7000'? Set the MCP for 120' then 7000 and so on. This will MAKE SURE you do not bust the altitude you are cleared to. If you want the speed on descent please choose a SPD DEScent for the descent page on the FMC. This will also keep restrictions at wpt places in altitude and then resume a speed descent ingnoring the path. [h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/forum/betaimg.jpgAMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | WD SATA 80 GIG | 512 DDR 400 |

Thanks for the reply. I will try your suggestion about SPD Descent when I have time. However, the essence of my post was this. If one has to set target altitudes on the MCP with each change, what is the point of entering that information in the FMC? Also, it sounds as though you are suggesting leaving VNAV on all the time.Jim O'Brien

> If you ask me (I have not seen his tutorial) this>284/12000 should NOT be a restriction because that>speed looks like a descent profile speed not a restriction for>an approach. Plus why would anyone want a speed restriction>above 10000' if it is not required? The constraint in the tutorial is just /12000, with no speed set.I agree, it sounds like the original poster wasn't in VNAV at cruise.

>Thanks for the reply. I will try your suggestion about SPD>Descent when I have time. However, the essence of my post was>this. If one has to set target altitudes on the MCP with each>change, what is the point of entering that information in the>FMC? Also, it sounds as though you are suggesting leaving>VNAV on all the time.>Jim O'BrienNormally you DO leave VNAV on all the time... where in that flight were you instructed to change to another mode?

indeed, you remain in VNAV and put ATC clearance limits in your MCP, if ATC cancels a certain alt restriction, you can put the new clearance limit in the MCP and push ALT intv. and it will descent to the MCP set altitude cancelling the restrictions up to the MCP alt when climbing and down to the MCP alt when descendingCheers

First of all, thanks very much for clarifying the use of VNAV. I had erroneously assumed that after climb to altitude, it should be turned off. My eyesight was apparently too good in that while only 12000 was commanded in the tutorial, the FMC example on p.71 showed 284/12000 and I thought I was supposed to enter that as well. Again, thanks very much.Jim O'Brien

No problem Jim. Learning is the main reason I think we all share here. I think the most important thing that I have learned is to look a the big picture when flying and using all of the automatics. If one way does not produce the desired result then try option b,c or d. Take a descent profile as our example. After setting up the FMS the FMC calculates a path from the E/D (end of Descent point) to the T/D (Top of Drop or Descent) at idle and displays a target speed (winds will effect this) but the default PATH MODE will only keep the path and not the speed. So one is above the airport restriction (250/10000) and their target is say 284 but your speed can become faster or slower depanding again upon WINDS. You can hlep the FMS if you are a bit slow by manually increasing thrust (on the PMDG NG this is accomplished by holding down the F4 button and releasing) or slowing by putting out the boards (Spoilers). Good thing to know here is that VNAV will NOT disconnect if the speed exceeds 15 knots like it would below 10000', you will still get the DRAG REQUIRED message when speed increases by 10 knots. If the speed reaches the Barber poll (actually 1 knot prior) the AFS will revert to LVL CH. So what this means is you have some leeway and time to get speed under control. No pilot in the real world expects to just push a button and not monitor what goes on, he actively monitors and takes action anytime the automatic flight system does not perform in the way he thinks it should or does something unexpected. So whether the autos are engaged or not simply does not mean that we not pay close attention to the situation, if anything we need more vigilance when autos are engaged. Some things to know about VNAV1] Path descents follow the path angle down not speed2] Speed descents follow the speed not the path angle.Both will keep restrictions and you might have to help slow at times3] Control the speed manually in PATH when needed4] Don't expect VNAV to perform wonders, if the flight path angle exceeds 7 degress VNAV descent it will ddisconnect above 10000' and 6 degrees under 10. What this means is do not place restrictions to CLOSE to each other because the plane needs time to descend properly. At excessive angles this bird will overspeed.5] Set the MCP Altitude window to each clearance altitude why? Well it's not that the AFS will not keep the restriction but why take the chance? You are cleared to that altitude set that altitude. Two other good things area: You KNOW it will not go under the altitudeb: Vnav will stay ENGAGED (make sure you use the VNAV ALT OPTION in the PMDG MENU). Simpl reset the MCP and push VNAV button to resume a descent.Last try LVL and V/S modes after you master VNAV modes. V/S is a fun way to control your descent and forces one to pay close attention to what's happening on descent.[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/forum/betaimg.jpgAMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | WD SATA 80 GIG | 512 DDR 400 |