A320 FMGS landing wind insertion
Thread Starter
Joined: Jun 2008
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From: Moscow
May be you are right about shoes and bombs when in flight. But I have been almost fighting with my friend on ground about this horseshoes - and it is already big deal for us. When wind is strong - Vapproachtarget is strongly different during wind variations.
Joined: Oct 2007
Posts: 98
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From: Greece
I would put 30kt headwind in the FMGS and compute landing distance (QRH) with zero headwind. In the worst case scenario (zero headwind at time of touch) I would have +5 knots on my Vapp (Vls+10 instead of Vls+5).
On the other hand if I put 0 headwind in the FMGC and in the worst case I had 30kt headwind at the time of touch, instead of the needed Vls+10 I would have Vapp+20kt (GSmini, which in our case is Vapp-10, plus current wind component) that would be Vls+25kt. Not true?
On the other hand if I put 0 headwind in the FMGC and in the worst case I had 30kt headwind at the time of touch, instead of the needed Vls+10 I would have Vapp+20kt (GSmini, which in our case is Vapp-10, plus current wind component) that would be Vls+25kt. Not true?
Joined: Oct 2007
Posts: 98
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From: Greece
It depends. Suppose steady wind conditions at final until touch (Gs mini not affecting target speed), highest target speed i.e. Vapp would result from inserting highest headwind component (Vapp= the highest of Vls+5/Vls+one third of headwind component). Or not?
Joined: Apr 2004
Posts: 509
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From: United States of Europe
You would still respect the Vapp=VLS+5 or VLS+1/3hw (whichever higher).
I refer to inserting the lowest possible headwind component as the TOWER WIND. (in case of variable winds, eg: in case of VRB05kt: 5 knots of tailwind)
In this way Vapp target will benefit from a higher GS MINI.
I refer to inserting the lowest possible headwind component as the TOWER WIND. (in case of variable winds, eg: in case of VRB05kt: 5 knots of tailwind)
In this way Vapp target will benefit from a higher GS MINI.
Joined: Oct 2007
Posts: 98
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From: Greece
Inserting a component of less than 10kt headwind or any tailwind does not affect target speed. GSmini for these insertions is Vapp-10. So target speed at approach would be the highest of Vapp/GSmini+current wind component (headwind counting positevely).
In Boroda's extreme example inserting 270/30 would result in a Vapp=Vls+5 and if for some reason GSmini function was unavailable you would not respect the required Vapp for the case of 180/30, which is Vls+10.
GSmini function is supposed to provide a kind of protection along the final approach flying into increasing headwinds and shortly thereafter into decreasing headwinds by maintaining a minimum groundspeed. It is not supposed to substitude the increment on the Vls due to the variable wind at touchdown. Ending up potentially in Boroda's example at threshold with target speed Vls+25 is not exactly what GSmini was ment for. Was it?
In Boroda's extreme example inserting 270/30 would result in a Vapp=Vls+5 and if for some reason GSmini function was unavailable you would not respect the required Vapp for the case of 180/30, which is Vls+10.
GSmini function is supposed to provide a kind of protection along the final approach flying into increasing headwinds and shortly thereafter into decreasing headwinds by maintaining a minimum groundspeed. It is not supposed to substitude the increment on the Vls due to the variable wind at touchdown. Ending up potentially in Boroda's example at threshold with target speed Vls+25 is not exactly what GSmini was ment for. Was it?
