Add final approach speed to HUD


It would be great if the final approach speed (given weight and selected flaps setting) was show on the HUD.

This would assist greatly with flying the correct final approach speed given aircraft weight and configuration.

Attached is a pic of the HUD on a real life 737-800. On the left side is the speed tape with a barber pole above and below the airspeed range you should fly for final approach. This is an idea that could be implemented on the IF HUD for each aircraft.


Pic is courtesy of The JetHead Blog.


Cool pic, thanks for the interesting post

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Yes, this is a good idea but I am out of votes however, I can’t see the devs doing this.

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I think it would be a great idea.

The speed & altitude lines that fluctuate indicate predicted future speed and altitude based on how the aircraft is being flown.

In my mind that’s a pretty advanced feature that not all real life aircraft have. As such, I’m hopeful
that a final approach speed range could be implemented as that would likely be a lot easier to implement.

We already have a barber pole to help prevent overspeed, the same concept can be used to show stall speed, etc as explained in my post and shown in the pic.

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Just to clarify a few things as shown on the HUD (replicated from the PFD).

The bug on the speedtape shows the bugged speed on the MCP - in this case 152 and also shown at the top of the speedtape. On a Boeing this is just taken from what is in the MCP speed window. Once you open that speed window on the approach you continually bug down the speed as you start putting out more flaps. If your autothrottle is in then the autothrottle will aim to maintain the bugged speed, if it isn’t engaged then it is up to you to maintain the bugged speed. When that speed window is open you can set that bug to whatever value you want, it isn’t directly taken from the FMC.

There is a Vref speed calculated in the FMC for the weight and flap setting intended to be used for the landing and this is indicated on the speedtape in the PFD showing “REF” in green and also in purple in the bottom left corner. I am not as familiar with HUDs so I am not sure if the Vref speed is displayed in there too.

In terms of the barber poles and the small bars at the top/bottom of them they represent safety critical limits rather than the limits of where you should aim to maintain your speed on the approach. Once you are fully configured you should aim to maintain your speed within +10 kts or - 5 kts of your final approach speed (Vapp which is Vref + wind correction). This is a much tighter range that shown between the barber poles & bars. This +10 to -5 range from the Vapp is not indicated on the speedtape.

At the bottom end the bar show the limit of your minimum maneuver speed and the barber pole indicates the point the stick shaker will start - you should never be anywhere near these limits. At the top end the bar shows the maximum maneuvering speed with that flaps setting, so it should be the same as the flap limit speed. The range in the photo shown between the upper and lower bar is much broader and looks around 30 kts but tbh if you speed is varying that much on the approach you are not stable and should go around.

So an important point is that the range between bars/poles is much broader that the range at which you should maintain your speed during the approach.

In terms of the feature request it would be great to include maybe the Vref speed on the speedtape and the bars/poles. I guess this would be a lot of work though to develop.

Exactly what ATK says.

A lot of this is calculated in the FMC, so it’s not just to “display” the v-speeds on the HUD. They would then also have to implement Vref calculations for the different aircraft types etc.

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