Hi allIve read thru the manual at least three times now, and Im still not quite understanding how to properly use VNAV. As far as I know, the FMC has been configured properly and EXEC. After taking off from the active, I engage LNAV and it works beautifully except (1). Then at @ 3000 AGL per the manual, I engage VNAV and it climbs to the initial altitude in the Rte/Legs pages and holds the airspeed, but after passing that waypoint, it never climbs or decends to the next waypoint's preassigned altitude/airspeed. What am I doing wrong?(1) Does LNAV have the ability to limit it's bank, so the passengers dont get thrown side to side when making a heading change per the FMC to the next waypoint? I thought that the bank limiter would do it, but it only works when using the MCP's HDG.Thanks,Eric

Eric,The FMC automatically calculates the bank angle when the aircraft is in LNAV mode. This cannot be changed, the bank angle limiter applies only to the Heading select mode.As for engaging VNAV, sometimes this happens me, pressing VNAV once(to disarm it) and then immediately pressing again to re-engage it might work. That is provided the MCP altitude is not constraining the aircraft.John http://homepage.eircom.net/~eamonnmca/images/logo_ba.JPGwww.bavirtual.co.uk Senior Captain Simflight.com Staff Reviewer

VNAV is limited to the MCP ALT settings! If the FMC wants to climb from 6000 to 24000 but your MCP ALT is set to 12000, VNAV will stop and level off at 12000! Setting the MCP ALT to 24000 (or higher) will enable VANV to continue the climb.If the FMC wants to descend from 18000 to 8000 but the MCP ALT is set to 13000, VNAV will stop and level off at 13000! Setting the MCP ALT to 8000 (or lower) will enable VANV to continue the descent.

Hi Eric,this kind of problem in the climbs is new for me, but there are some strange behaviors in the descends, which were discussed and confirmed (Thanks Mats) in the thread below. As John have said in his post above, the only way to solve it, is re-engaging the VNAV.http://forums.avsim.net/dcboard.php?az=sho...&topic_id=57114Jorge Niny

There certainly is a 500 FPM issue with HARD constraints that are close to each other or close to the 250/10000 AirPort restriction that will cause reversion to LVL CH or CWS simply because it cannot meet the restriction (Real issue here). Here is a hint, if you expect many restrictions do not use VNAV PATH. There are other ways to fly this plane and all of them are realistic i.e. V/S, LVL CH, VNAV SPD. You guys with this descent issue try it in VNAV SPD and tell us if you still have the problem, I would be suprised if you did... I doubt this is the issue for the orginal poster. Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

Okay, this VNAV thing is really beginning to get under my skin. I have flown at least 6 or more flights just for the purpose of learning how to fly with VNAV. Just to make sure that I have the routine right, here is the process I have used:Bring systems on-line, get FMC programmed via CDU with all data entered for initialization.Program FMC with Nav Data. Example: Set Cruise for FL310 KSGJ RWY13CRG/270kts/12000SSI/280kts/FL180AYS/.78/FL310VQQ/240kts/10000MONIA/210kts/3500DINNS/180kts/2000KJAX RWY 7Line up on the runway, engage TOGA after 40%N1Rotate at VrClimb to 2000AGL, engage APPass 3000AGL engage LNAVEngage VNAVAircraft flies the LNAV profile, and flies to first assigned altitude of 12000, but never begins climb after passing CRG to SSI assigned altitude of FL180. Fails to follow VNAV profile of decent to 10000 at VQQ, and a manual decent is ordered via the MCP. Now, I have tried altering the MCP ALT window to the highest altitude setting for the flight profile, but I assume I have to lower it to 2000 when I go to begin my decent for waypoints AYS thru to DINNS ?This morning after trying once more, after passing 3000 AGL, pressing VNAV, it would not even illuminate. AND, I insured that the altitude in the ALT window was set higher than the max waypoint altitude profile. What gives? I know that as much time and effort that PMDG has put into the product, I MUST be doing something wrong. This seems to be erroneous to me. Back in FS98, a Japanese gentleman created a freeware program called Nav Dash that once you put in the Altitude and Speed restriction, the a/c followed that profile.

"Okay, this VNAV thing is really beginning to get under my skin." That's what I told my ex wife, just replace the word "VNAV" with your imagination '-) You can ARM LNAV on the ground. You must be within LNAV's criteria for LNAV to engage. You can turn on the A/P at 400' (i.e select a CMD is what I mean by A/P engagement) "SSI/280kts/FL180" What is the purpose of this wpt? Did you input this yourself into the FMC? " but never begins climb after passing CRG to SSI assigned altitude of FL180." This one too? As a pilot one thing you do not want are a bunch of restrictions and if they are not part of a airport procedure certainly don't make life harder for yourself by adding unnecessary wpt restrictions to your route. Program the FMC leaving out ANY wpt restrictions except the ones called for in your sid and star. Set cruise altitude on the MCP (unless you have ALTs you will level off to or at or BELOW "B" restriction) then set the MCP to that. Takeoff, @ 400' engage LNAV, start retracting flaps @ 1000 AFE or 3000 AFE depending on the procedure, push CMD A (at this point you are in LVL CH as pitch mode) and speed up to flaps UP maneuvering (Set MCP speed dial to the UP bug shown on the PFD), THEN speed up to 250 knots and engage VNAV (Smoother transition to VNAV if you are already close to VNAV target speed). "This morning after trying once more, after passing 3000 AGL, pressing VNAV, it would not even illuminate. AND, I insured that the altitude in the ALT window was set higher than the max waypoint altitude profile. What gives? I know that as much time and effort that PMDG has put into the product, I MUST be doing something wrong." Could be many reasons. Can the aircraft FLY the restrictions you had programmed? i.e. can it reach it in the time frame at the speed? When you press the VNAV button what MODE is the plane in before pushing the button? Hand flying? HOW FAST ARE YOU GOING WHEN YOU TRY TO ENAGE VNAV? Why my caps? Because it is very important for you to know that you must be in VNAV CRITERIA to engage VNAV. What is that? Well if your are Below 10000' your speed MUST BE within 15 knots of the VNAV climb target. And this I believe is why you could not engage VNAV. This plane is complex and like anything the requires this much learning can get under our skins. Not only do we need to learn what the real world technics are but also FS quirks to work around like making sure you don't click on the speed brake but insted drag it to ARM for them to deploy. All this learning takes time. This forum has everything you need to know on how to operate this aircraft correctly. There is enough information and helpful threads to keep one busy for months. Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

"Below 10000' your speed MUST BE within 15 knots of the VNAV climb target. And this I believe is why you could not engage VNAV."I didnt realize THIS part...thanks Randy! I know it's a great aircraft, and I have spent more time in the manual. Thanks,

Hi Randy - many thanks for your continuing assistance to everyone.Your comment "...You must be within LNAV's criteria for LNAV to engage..". Did you mean VNAV in place of one of the LNAV's? If so, do you know why that is a requirement?Cheers, Chardy, in OZ, where we make the BEST chardonnay in the world, outside of France!!

No meant what I said. I believe it is within 3 miles and 5 degrees at least on TO, would have to look it up if there is more, maybe after TO on an intercept to course within 3 miles....Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |