Non precision approaches

[Guest jacaru]

Hello all,It has been some time ago since I own the PMDG 737 but I have never worried to correctly perfom non precision approaches. Almost all the time either i use an ILS approach or visual using manually V/S.But since the last couple of days i have been interested in doing these as they are suposed to be done. I have read the manual many times and been looking for info here about them, but i have many problems.My first big difficulty is not getting a VNAV disconnect on initial approach. I enter the correct speeds and altitude restrictions (i dont use soft altitude restrictions since i have read they not work so good).For example lets take PHKO RNAV approach rwy 35. I take off from that same rwy and proceed directly to ANDES intersection at 5000 feet. After ANDES i have set this waypoints and restrictions:HASOG01 (HASOG174/15)HASOG 180/2000HOXLY 155/1700RWY35 /47HASOG01 is there so that the airplane does not cut through much coming from ANDES.The MAP is RWY35 and missed approach procedure is proceed to ANDES at 5000 and hold.With this setup, the T/D point is just before the turn to HASOG. But when i go over it the plane does not start descending and i begin getting a VNAV deviation up to 1000. Because of being late the plane then has to begin a steep descent and on top of that reduce from 250 to 180. At the DECEL point I have just descended from 5000 to 4000 and the plane then stops descending to reduce to 180. I have to take all out, gears and flaps 15 if i want to avoid a disconnection at HASOG. This is all on VNAV PTH. Should i use VNAV SPD?At this point i wonder if 5 miles before of T/D could be valid and useful to use speed intervention to 180 until HASOG so the plane starts decelerating a bit early. Would this affect the VNAV PTH following?Other option could be inserting more points/restrictions previously to force the plane plan the descend with more time?Then, reaching MDA+1000 feet I set the MCP altitude (previously set at MDA altitude) to Missed Approach altitude - 5000 feet. And surprise (for me since i must be doing something wrong), the plane starts climbing to 5000 feet. Do I have to hit APP button or something?Then i press TOGA to do the missed approach procedure and autopilot disconnects. When i enable autopilot again it goes to HDG SEL, and if i hit LNAV it says "no interception course". So i have go to the LEGS page and do a DIR TO ANDES and then LNAV. I though that once you enabled TOGA the plane would climb to missed approach altitude and that passing over the MAP would proceed directly to ANDES. Maybe getting confused with Airbus stuff.Please bear with me since i have gone many places to try to document myself first and i have not found any reliable source. PMDG docs say somethig and other sources say the opposite. Im completely lost.Thanks for your help.Jaime.

[michal 44]

>Then, reaching MDA+1000 feet I set the MCP altitude>(previously set at MDA altitude) to Missed Approach altitude ->5000 feet. And surprise (for me since i must be doing>something wrong), the plane starts climbing to 5000 feet. Do I>have to hit APP button or something?When you reach MDA you have to wait for airport to come into view. If it does then disconnect autopilot and fly/land manually. If you reach MAP (missed approach point) or otherwise have no chance of landing then execute the missed approach and the first order of business will be adding the go-around power and setting the MA altitude in the MCP window. APP button is only for ILS.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2

[zubart 5]

Jaime,I tried this and had the same problem. Your speed and altitude constraints are good and make sense. But, to fix it, delete the Andes 5000 feet FMC restriction. It should now work OK in VNAV PTH descent mode.Also, I would use a waypoint like IAI210/10 instead of the HASOG174/15 because the airplane will make the turn to final easier.When about 1000 feet above MDA I too could only reset the MAP altitude to 4400 feet instead of 5000 feet. Vnav disconnects and the airplane enters ALT HOLD. This happens occasionally with other approaches and I don't know why. If it does happen, just reset the MCP altitude lower and push VNAV again.Only a duel autopilot GA is available in the 737NG. Floyd