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ronzie

LNAV engagement after departure vectoring

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The LEGS display of the active route shows the correct bearing to the next waypoint but after using heading select for vectoring and then engaging LNAV the aircraft turns away from the LEGS bearing displayed and wants to return to the original track. Doesn't the current bearing to the next point take effect or do I need to force a direct-to even if the first bearing and point at the page top is correct.What am I missing in getting a direct-to for the top listed waypoint to get a path updated from PPOS to the next point. I know how to skip and add waypoints and close discontinuities. Thanks for any help.PMDG 737NG 600/700/800/900 with current sps.


Ron Ginsberg
KMSP Minnesota, Land of 10,000 Puddles
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I've noticed this too with the 747-400.Prior to TO, Lnav will have a nice SID all entered in legs/route pages and on the ND. In the case I'm thinking of, the Lnav track will require a 180 degree turn after TO. I'll blast off on runway heading and continue in that general direction for a while. I'll be trying to play around with hanging on some V speed or other, then get up to 10,000 ft and remember, "Oh yea, I was going somewhere." The Lnav track is well behind me now. I range up and select the ND to center. There is is. Way back there. I select Lnav. The results are erratic and never what I want. I want to fly back to the Lnav track. It'll go this way then that and wander around and finally say, "OK, enough." I'll 'heading select' toward the track. When I am within a couple of miles and on a graceful intercept, I engage Lnav. I am then faithfully flown right on over and hooked right up to my previously illusive track. No problem.When I'm still out there a ways, I could just select the closet Lnav waypoint and have Lnav 'connect the dots' (go direct) between me and that waypoint. But that would work for sure, so it's not near as much fun. No answer, just seconding the question.

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For LNAV operation four items must be fulfilled.- LNAV Armed- An active flightplan must be set in the FMC- Radio Altitude is above 50 ft- Aircraft must be in a 2.5 nm area from Active LegB. rgdsMichel

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>- Aircraft must be in a 2.5 nm area from Active Leg>>B. rgds>>MichelThat's the one I was not aware of. Also I was in the general direction of the next waypoint and did not get the intercept out of range status message so I thought all was OK. There was no status message, LNAV was indicated as functional, and the lack of indication except my monitoring heading showing the unwanted bearing confused me. I am aware of the limitation of a few degrees on heading intercept range but no matter how I pointed the aircraft it would not do the correct thing.So the question is, how do I refresh the first leg - departure airport to first waypoint of about 125 nm - so the active leg is from PPOS to said waypoint - if it can be done. I've just been using heading select until I was within track intercept range.Thanks for catching the limitation I missed.


Ron Ginsberg
KMSP Minnesota, Land of 10,000 Puddles
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