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Guest allblack

MCP heading v true heading

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Guest allblack

Gidday all.Quick question about headings.I'm presently @ FL33 with a heading of 165 in the MCP. The wind indicator is saying 283/66, but my true heading is showing as 156.I'm flying with ATC, so have the HDG on and not LNAV.So, my questions are:1/ Why does the plane not take into account the wind and fly the heading in the MCP? Do I need to be doing something different??2/ Why does this happen when HDG is being used? - if I was using LNAV then this wouldn't be an issue.3/ Again this isn't an issue the the default 737, the plane tracks as per what's put in the HDG.I'm presuming this is part of 'as real as it gets', so keen to learn why 'real' means the plane flys 8 degrees off what's been inputted. The pink dotted line is pointing at 165, and it has the white upside-down triangle right on top of it. ( The white triangle can be a question for another day!!)I'd do a screenshot, but don't know how! However, the answer may not require it anyway.CheersTim

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Hi Tim,1) Because this is the way any real aircraft works. When you set the autopilot to a specific heading, it will hold the heading reguardless of the wind. You

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Guest allblack

So....even though the ND shows 156, I'm actually heading 165??Seems bizarre to me. How would a pilot know he's going in the right direction, or would he just trust the MCP (and Boeing!)and assumes "she'll be right"?"LNAV is navigating to a specific point, hence the system takes into account the effects of the wind."Why doesn't HDG do this?If the heading in the ND agrees when LNAV is selected in the MCP, then why can't it do the same when HDG is selected?Appreciate your comments, and I'll mull over them a bit more over brunch. I can't believe after all these years of 'flying'. I'm bamboozled on something as simple as this! Guess that's what happens when you move out of the default planes!CheersTim

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I think you are confusing a few terms here:first of all, lets define true and magnetic heading. As you probably know, the magnetic north pole is not directly on the geographic north pole. If you fly a magnetic heading, you are referencing your heading to magnetic north. Fly a true heading, and you'll be using the geographic north pole as reference. The difference between mag and true heading is called variation or declination.Then there's grid heading but lets keep it simple!Now then forget true heading as it has got nothing to do with your questions.Remember: a heading is not where you are going, but to where your nose is pointed to. Thus, heading will not be dependent on wind. If you set a heading of 155

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Guest allblack

Phew! Thanks Mark.So, even though the ND shows 157, I AM going in the direction of 165?I assume then although the nose is pointing to 157, I'm sliding, for want of a better word, towards 165 (ground track?)?So then what's the relationship between the heading on the ND (157), the pink dotted line pointing towards the MCP heading (165), and the inverted white triangle that seems to move around between the two on the compass rose? Is that the "pointer" you mentioned in your post?If so, you said it represents my heading. But isn't my heading 157 i.e. where the nose is pointing?Learning heaps here! Thanks again.Tim

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Guest ahmedem

As far as I know....MCP is where you enter your heading.12 o'clock position on the ND is your ground track.Inverted white triangle is your current heading, this will line up with whatever is in the MCP when the AP is in HDG SEL.The magenta dotted line and corresponding heading bug is the requested heading in the MCP.As a side note on Airbus aircraft the have a track/flight path angle mode on the AP so that the pilot can choose heading and not worry about compensating for wind.Hope I'm right about all that, and hope it helps,

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Guest B1900 Mech

The PFD,or primary flight display is heading up, And the ND nav display is track up.:-)

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Here's a nice picture of an ND:http://www.airliners.net/open.file/402147/L/As you can see, this NG also has the "track up" mode installed (its a company option).The aircraft is flying a track of 138 degrees. Heading is around 146 (the white triangle). The MCP heading selector is set to 145 degrees (the magenta thingy). You can also clearly see that the small compass rose on the PFD is heading up and not track up!Regards,Mark

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"...And the ND nav display is track up."Well, at least it is in MAP mode. PLAN is TRUE NORTH, APP and VOR are heading up ;-)Cheers.Ian.

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