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Old 12th Sep 2015, 18:44   #1 (permalink)
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tailwind landing

To the Airbus gurus in this forum:

Let's assume a long and dry runway (e.g. >4000 m) and a relatively light weight A320.

Considering landing distance is not a concerning factor, what would be the best or recommended landing configuration in a tailwind situation? Flaps 3 or Flaps Full?

Without thinking too much, most common answer is flaps full. But according with my experience I tend to believe that the "cleaner" configuration allows a much better and smoother handling.

Thanks
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Old 12th Sep 2015, 19:09   #2 (permalink)
 
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I presonally don't like Conf3+tailwind combination on the A320, due to tail clearance issues. In TW conditions you carry no extra speed, so have a higher approach pitch attitude to start with. Then, since you have higher ground speed and sink rate, you need even more pitch during flare... These effects combined leave not much room for mishandling which can happen on a bad day.

So, for my personal comfort Tailwind=Conf Full, even on a long rwy....
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Old 12th Sep 2015, 19:51   #3 (permalink)
 
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The length of the runway = the distance to the planned exit!. Plan accordingly.
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Old 12th Sep 2015, 22:12   #4 (permalink)
 
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Say the wind at 500' is a 30kt TW and the wind on the runway is a 5kt TW. Flaps 3 probably won't have enough drag to decelerate the aircraft during the approach as the tailwind dies and maintain whatever stable approach SOP's you use. Hence, despite the fact that you can make a smoother landing, can you make a safe approach?
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Old 13th Sep 2015, 15:11   #5 (permalink)
 
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Smoother landing could be the last thing on mind in tailwind. First because of the higher ground speed you feel closer to the ground than you are and tend to flare high. If that happens the float seems eternal and you would rather call it a day by putting it down. If you can flare little lower and little less than normal, a smooth landing is possible on the correct touch down point. On a long runway if you flare high as I said before and float then the factor C_star is talking comes into play. It depends on how much finer seat of the pant feeling you have. That is the only skill left in the airbus rest is automatic and done by computers.
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Old 13th Sep 2015, 16:38   #6 (permalink)

 
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I don't know that I've noticed all that much difference. Then again, I usually only use Config 3 when the airplane is so light that the Vapp for Config Full is embarrassingly low.
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Old 13th Sep 2015, 19:00   #7 (permalink)
 
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Company policy is to ban Flap3 landings in the A320 but we can do them in the A321. We fly some very heavy 321s (Cat D)so I would be be reluctant to reduce the flap setting with a tail wind. The thought process is how much energy you are trying to disspate on touchdown so why hammer the reversers and brakes to save a few kilos of fuel by landing with reduced flap.The touchdown quality doesn't seem to be any different.
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Old 14th Sep 2015, 09:02   #8 (permalink)
 
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Hi C_Star,
Quote:
Then, since you have higher ground speed and sink rate, you need even more pitch during flare...
Why do you need even more pitch change during the flare?
If you were on say a 3 degree slope, then flare by 3 degrees, you would fly level (with same IAS).
Surely all you have to do is commence the flare earlier due to rate of descent?
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Old 14th Sep 2015, 09:31   #9 (permalink)
 
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The way I understand it - with tailwind you'll have higher sink rate for the same glide path angle.

To arrest higher sink rate you either need to flare higher, or more aggressively. Hence, in my opinion at least, there's increased potential for tail strike, esp. if you get the flare height wrong...

Increasing pitch by 3 degrees to fly level with the same IAS works in steady state, not in flare, where you need extra lift to change the flight path. Then add another degree or to of pitch to compensate for decreasing speed during the maneuver...
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Old 14th Sep 2015, 10:19   #10 (permalink)
 
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All theory aside, an A320 will tend to float with any kind of tailwind. Hardly any flare is needed with a max TW. If you flare, you'll float.

F3 or Full? Personally I will only consider F3 in the most benign tailwind conditions, i.e. stable tailwind, no thermals, exactly on profile. If you get high on profile with a tailwind and F3, you WILL loose speed control. Same with thermals, your speed will run away with the engines at idle all the way down, especially in the A319.
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Old 31st Oct 2015, 08:24   #11 (permalink)
 
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Cough, Why do you say you won't have enough drag? If you have at 500 ft 30 kts tailwind and at 50 ft 5kts tailwind you will need thrust not drag...
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Old 31st Oct 2015, 09:04   #12 (permalink)
 
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Err...no.

A reducing tailwind is an example of overshoot wind-shear, and you would indeed need less thrust/more drag.
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Old 31st Oct 2015, 13:24   #13 (permalink)
 
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If Tailwind reduces from 30 kt to 5 kts, due to inertia, KIAS will increase 25 Kts. Yes you need drag for deceleration.

if you are approaching with F3 and TW, pitch attitude or cockpit perspective will be relatively close to the Full Flap and No TW. That could be good for landing, provided more pitch up required during flare.
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Old 6th Nov 2015, 16:53   #14 (permalink)
 
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Why for god sake would you do a F3 landing? On a 319 for practice purposes yes just to keep used to the picture as quite a few non normals require F3 for ldg. But why would you do a F3 in a 320 with tailwind?? Its harder to get the a/c speed stable. It feels like the a/c is hanging in the sky and speed fluctuations are much more present then with F-full. With some bad luck you end up with thrust in idle on short final. Even in gusty conditions i am not a fan of F3 but thats personal. Flare gives less margin for error and the possibility for a "pitch" callout increases big time. Only in very few situation I prefer F3 but otherwise I dont see the benefit!
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Old 11th Aug 2017, 01:14   #15 (permalink)
 
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Some people above have said that little flare is required with a tailwind.
Why would this be the case when you typically have a higher ROD to maintain the glide?
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Old 11th Aug 2017, 07:38   #16 (permalink)
 
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Anyone who deals with real world repetitive tailwinds, will attest to the fact that a standard flare WILL result in a float. After a while you get a feel for it. The only way I can describe it is that the aircraft is quite reluctant to settle down. After a lot of trial and error it becomes predictable and you will know just how little of a flare you need for a perfect tailwind landing.

Why?
One of my theories is that the indicated airspeed (IAS) increases on a tailwind landing. Think about it. In a headwind landing you will often loose a few knots during the last 30 feet of the approach due to the decreasing wind. The same happens during a tailwind, however as usual, a reduction in tailwind will lead to an increase in IAS. And it is this increase which will lead to a floating tendency. This is just my theory, nothing else.

Other avenues to explore are the higher ground speed and its effect on ground effect..
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Old 11th Aug 2017, 16:57   #17 (permalink)

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Normally I close the TLs at 30 ft, flaring at 15. With tailwind, the best results for me is to close at 45-40, flare only slightly at 10. My theory is the same as PENKO's.
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Old 11th Aug 2017, 17:25   #18 (permalink)
 
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‘P’, the point you overlook is that there is no ‘standard’ flare. Landing is not an open loop step input, but a dynamic reassessment - how goes it, involving adjustment for the start and during the manoeuvre. We learn and improve with practice of how to adjust our inputs during the flare.
Some theories suggest that the assessment involves the comparison of height and height rate, with feed back including pitch attitude, and stick displacement or force. Further moderation and feedback involve time and most important projected point of touchdown.

The Landing Flare of Large Transport Aircraft.

For the OP, if you do not wish to follow the maths in the report, at least scan the many figures at the end which may provide an answer; at least an education every time I look at them.

My safety view is that distance is always a factor, smoothness is just a resultant nicety of practice. It may be easier to gain experience from practice by concentrating on one normal flap setting.
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Old 11th Aug 2017, 18:25   #19 (permalink)
 
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Safetypeee, of course it crossed my mind that it might all be an illusion. But how do you explain the fact that in a ten knot tailwind you can almost fly the plane down to the runway without any flare? The effect being a buttersmooth landing, of course. Don't do that with a headwind!

*disclaimer: the above is my experience, after more than 300 tailwind landings in just a few years in a very tailwind prone base. Use your own flare technique, but keep in mind what I wrote, and adapt from there on. In no way do I prescribe an non-standard landing technique!
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Old 11th Aug 2017, 20:18   #20 (permalink)
 
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Quote:
Originally Posted by FlightDetent View Post
Normally I close the TLs at 30 ft, flaring at 15. With tailwind, the best results for me is to close at 45-40, flare only slightly at 10. My theory is the same as PENKO's.
Given that the FCOM states that normal flare height is 30ft that is very surprising.
The FCOM says that a late flare will likely result in a hard landing.
Especially if you retard the thrust levers high, you will tend to lose speed hence reduce the flare efficiency..

So could you tell us more about your landing technique ?
Thanks
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