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downscc

Decent Screen Question

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I'm flying the 737-700 on a normal decent see on the lowest line of active text: FPA V/B V/S ?? I've got V/S figured out, that's the verticle speed ft/s target for the FMS. I have double checked my operators manual but can't find FPA and V/B. Anyone know?Dan DownsKCRP


Dan Downs KCRP

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Guest joediamond

FPA - flight path angleV/B - vertical bearingC McCarthy

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Wow.. makes sense. One more descent question (I just learned to spell): During descent or climb I see a green arc moving around on the nav screen in plan mode... it seems to have something to do with TOC or bottom of descent but not exactly. What's that green arc?


Dan Downs KCRP

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Guest joediamond

That's the point at which you will reach the altitude selected in the MCP window.C McCarthy

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Thank you again... I sincerely appreciate the help. After awile, I started to notice exactly what you attribute the green arc to mean. Pretty nice tool.


Dan Downs KCRP

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Guest Daniel Slade

Very usefull if ATC clear you to a "level by" e.g "....descend 14,000 level by Biggin" So you would us V/S and set the green ark on or just before BIG "Biggin" VOR.Hope this helpsDaniel

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The VBI provides 3 fields:

  • FPA (Flight Plan Angle) is the vertical path in degrees that the aircraft is currently flying.
  • V/B (Vertical Bearing) is the vertical path in degrees that the aircraft SHOULD be flying to reach the keyed waypoint.
  • V/S (Vertical Speed) is the vertical bearing (V/B) converted into vertical speed for easy input into the MCP.

FPA is the actual flight path angle of the aircraft. It is typically 3 to 4 degrees in a descent.

 

V/B is the required vertical bearing to reach the WPT/ALT. This would be an altitude restriction in the LEGS page that you could enter (or delete) manually or with the ALT INTV button on the MCP.

 

V/S is the required vertical speed to make good the V/B.  

 

As you approach your ToD the FPA will remain at zero (because the aircraft is in level flight), but the V/B and V/S will both increase until the V/B is at about 3 to 4 degrees, or whatever the FMC has calculated is the optimum value. If VNAV is engaged the aircraft will descend with a FPA equal to the V/B. The actual V/S will however be slightly different to the computed V/S because V/S changes during the descent.

 

Read more about the FMC:

http://www.b737.org.uk/fmc.htm

 

This is also informative:

http://www.flaps2approach.com/journal/2012/7/23/vertical-bearing-indicator-vbi-how-to-calculate-a-controlled.html

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Better late than never...


Regards,

Bob Quick
 

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LOL a post from back when I was just getting started with the FS9 NG.  Thanks thomas.ljung; however, PMDG prefers the use of full names in the post even if your screen name is your name.


Dan Downs KCRP

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