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Guest davidbernard

737NG LNAV & VNAV arm before engaging AP

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Guest tomahawk_pa38

Jose,great clock - where did you get it from ?

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>Jose,>>great clock - where did you get it from ?I downladed a clock gauge from Avsim (I really don't remember the name, there are a lot of clocks...) and I modified it by myself. (It is the type of gauges you can edit in wordpad)Jose Luis

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>Also, LNAV is not ARMED in this case, it is already ENGAGED as>seen >by the green LNAV on the FMA because LNAV engagement criteria>on the ground has been satisfied.Floyd, I was not aware that the LNAV mode could be engaged on the ground, the PMDG manual makes mention only of arming it on the ground and the fixed-base 737NG sim I work in behaves in this way.I wonder if the original poster's set up has been confused by some combination of circumstances, because as I understand it, what the screen shot shows us is not possible.Comments anyone?


Mark Adeane - NZWN
Boeing777_Banner_BetaTeam.jpg

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Gents,The last couple of days flying with the NG I have paid close attention to the MCP. At no time have I been able to arm, or engage any mode before take-off. Not even for FD mode operations as mentioned above. As I remember this is as it should be.Comments?

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I am able to arm (or engage, as you like) LNAV on the PMDG 737 NG before takeoff but not VNAV.With the PMDG 747, I am able to arm both LNAV and VNAV before takeoff.I only say arm because the they don't control the plane until the autopilot is engaged, which is not until you get into the air. Only 'engaged' for FD purposes as pointed out in previously in thread.Just for information.Renzo


Bill Miller

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LNAV can not be ARMED. It's either engaged or it's not.A green mode color on the FMA means the mode is ENGAGED. A white mode color means the mode is ARMED. You will NEVER see a white mode color for LNAV on the FMA.LNAV can be engaged on the ground before takeoff if these LNAV engagement criteria are met. The PMDG 737 simulates this fairly accurately:-origin runway in flight plan-active route entered in FMC-track of first leg within 5 degrees of runway heading-LNAV guidance becomes active at 50 feet AGLGood luck,Floyd

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Yes, the 737NG's permit LNAV engagement before takeoff, but no VNAV engagement. This is accurate behaver to the a real 737NG.Yes, the 747-400 is a different type. It's autoflight systems and procedures maybe different. No, with LNAV engaged on the ground prior to TO/GA push, and after lift off, the FD lateral command bar will begin giving LNAV course tracking commands to follow the LNAV course. It does not require an autopilot engagement.Good luck,Floyd

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Guest benhoffman

At UAL its v2+20 (or +15 if gross weight in excess 117,000lb) at 400ft arm roll mode, at 800ft engage pitch mode and climb at ref30+100 or clean speed whichever is greater. At 3000 accelerate to 250kts and accelerate to ECON CLB.

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"A green mode color on the FMA means the mode is ENGAGED. A white mode color means the mode is ARMED. You will NEVER see a white mode color for LNAV on the FMA."Haven't thought about it before, but I guess it depends on your definition of "ENGAGED" :) LNAV is certainly not driving the FD or the ailerons when the aircraft is on the runway. The command is wings level until 50 feet, then LNAV becomes the FD roll command, so I guess it is sort of armed before then. The A/P on the other hand, AFAIK, cannot be engaged until 400.To the guys saying they cannot engage LNAV on the ground:1) Which version of the NG do you have?2) Have you made sure there are no options in the menus for allowing LNAV arm on the ground?Cheers.Q>

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