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Guest mpauli

non precision approach and VDEV

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Hi AllOne more time I would like to address something to all the other PMDG 737 pilots beside me. I was shooting an VOR DME Approach on runway 28 in LSZH (Z

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Most likely you don't have the altitudes entered in the LEGS page. Open the LEGS page and make sure all restrictions are correct, especially the waypoint you were trying to head to when it failed on you.Also, it's actually a bit better if you disconnect VNAV and fly using V/S and SPEED when starting your approach (6000 ft for you like you said earlier). Reason I say this is because VNAV can cause some problems, and you don't want that when on a manual landing.Nick B.Continental Airlines Virtual 737NG Pilothttp://www.precisionmanuals.com/images/forum/800driver.jpg--AMD Athlon XP 3200+ @ 2.2 Ghz (Equal to 2.8 ghz)400W Power supply3x 80 mm Case FansSoyo VIA KT600 Dragon PlusnVidia GeForce FX 5200 128 mb2 x 512 PC400100 GB Western DigitalMicrosoft Sidewinder Precision 2

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Did you remember to reset your MCP altitude? VNAV won't descend below your MCP altitude setting. After awhile if you have not reset the altitude there will not be sufficeint time to descend to meet the verticle path and a VNAV disconnect will occur with the error message you received.This sounds to be the cause. When you are shooting the ILS you likely have your auto-pilot in VOR/LOC and then in APP modes. If I remember correctly this puts your autopilot into the "MCP SPEED, VOR/LOC, G/S" modes; meaning you aren't in VNAV mode. Therefore, once you are tracking the localizer and g/s the AP isn't in VNAV mode and will descend below the MCP altitude.

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Thanks Ryan and Nick for your answersBut I did all of the things you mentioned right! I did the approach three times and it NEVER worked. Talking about entering altitudes in the FMS: as you can see from my attached part of the STAR file the altitudes were already given by the procedure and I rechecked them before starting the approach!I would fly the approach with V/S but this doesn't explain why the VDEV bar is totally wrong! It should be the main help flying the plane pitchwise during a VOR approach but it is useless!Any other hints? BTW: feel free to fly the approach yourself! All you need is at the Navdata.at website!CheersMartin

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Paul: It is in his original post.Martin: I have also noticed this. I think it has to do with non standard aproaches. I have created TACANS STARS for a few of the Navy bases in the US and I get the same thing. I program the restrictions exactly as they are on the STAR yet after it makes it's first altitude constraint it displays descent path unachievable

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Hi, I think this may be related to an incident I (and another pilot, eventually one of the beta team also got it) experienced when flying a STAR. What happened was that the airplane would meet the first altitude constraint (although at a slower speed than commanded). Instead of keeping the decend profile, the autopilot seemed more interested in catching up on the speed and continued a very shallow decend (approximately 500 ft/min) resulting in the eventual VNAV disconnect. Anyway, it has been reported to the team and they are looking into it.ThanksBoazEKCH

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