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dmwalker

Question regarding the Wind Direction/Speed indication on th

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What is the logic for when the wind direction/speed values are shown on the B777 ND?

In my case, they are not displayed at take-off until about 4400ft altitude. In some videos, they are shown just after V1. In the case of the PMDG Tutorial video, they were not shown at all.

Videos of real life take-offs don't usually focus on the ND but the few that I could see showed the values displaying at around V1 or VR.

There are similar differences during descent and landing, including real life videos.


Dugald Walker

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13 minutes ago, dmwalker said:

What is the logic for when the wind direction/speed values are shown on the B777 ND?

When there is wind - display it.

Most likely, the issue is that the wind is calm, so there's nothing to display.

The tutorial has you fly in clear weather, so this makes sense.


Kyle Rodgers

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The ND wind vector is shown when winds are above 5 kts I believe.  Should not have anything to do with phase of flight, I've seen it come alive during takeoff rolls.


Dan Downs KCRP

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Like Dan says wind has to be above 5 knots.  Additionally the true airspeed has to be above 100 knots.


Brian W

KPAE, KRNT

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I was going to ask about the airspeed. 100 knots makes sense as it seemed to be between 80 knots and V1.

Thank you.


Dugald Walker

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7 hours ago, dmwalker said:

I was going to ask about the airspeed. 100 knots makes sense as it seemed to be between 80 knots and V1.

Thank you.

Think about it... there is no direct wind sensor.  The wind speed and direction is calculated by the system based on IRS/GPS/DME sensors.  It cannot be calculated with any accuracy until the airframe is in motion and the value you see while on the ground is, ... well, I wouldn't put much confidence in the direction.


Dan Downs KCRP

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8 hours ago, dmwalker said:

I was going to ask about the airspeed. 100 knots makes sense as it seemed to be between 80 knots and V1.

Thank you.

For the last 50 plus years all I have ever cared about is KIAS.  The aircraft tells me the rest. 🙂

Grace and Peace, 

Edited by Bluestar

I Earned My Spurs in Vietnam

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52 minutes ago, downscc said:

Think about it...

That's the hard part for me - the thinking - but now I understand. Thank you.

 

31 minutes ago, Bluestar said:

For the last 50 plus years all I have ever cared about is KIAS.  The aircraft tells me the rest.

"Words of wisdom from one who knows whereof he speaks."

Edited by dmwalker

Dugald Walker

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