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I've seen a fair number of articles online about "The World's Most Useless Airport" (St. Helena, HLE/FHSH), which was unable to open to full commercial flights (as was the intention) due to the wind shear that occurs there. Because of this, only small aircraft are allowed to operate into St Helena.

This may well be a completely impossible idea, but if the issue is wind shear could they not adopt a system similar to this 'wind wall' which they use to protect large cargo ships in canals in the Netherlands?

Obviously we are talking about aircraft here and not ships, but would an approach like this - diffusing the wind either side of the runway threshold - have any effect on the final stage of the approach, to the extent that the wind sheer becomes tolerable for 'standard' commercial air traffic? Obviously large concrete structures wouldn't be particularly sightly, but from a purely practical point of view would something like this alleviate the issue at all?

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  • $\begingroup$ This is an interesting idea, but I think it might not be feasible as aircraft are much more sensitive to wind sheer than ships . If a ship is hit by a strong wind sheer it will drift to the side, if an aircraft is hit by a strong wind sheer it coulld end up side down. $\endgroup$
    – ROIMaison
    Commented Jun 19, 2018 at 11:49
  • $\begingroup$ Yes, I am sceptical anyway. I can't find very much information on why there is such bad wind shear for southbound landings and tolerable conditions for northbound landings, but one source seems to suggest it is the fault of the small mountain on the edge of the plateau at the northern end of the runway. Maybe some dynamite could solve the issue rather than concrete :p $\endgroup$
    – Ben Turner
    Commented Jun 19, 2018 at 12:16
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    $\begingroup$ Who do you think you are, Donald Trump? $\endgroup$
    – A. I. Breveleri
    Commented Jun 19, 2018 at 17:36
  • $\begingroup$ @BenTurner: Looking at the pictures, I would suspect part of the problem is downwind in southern direction. There's just nothing there, a steep drop-off in 3 directions. If you've got wind blowing from the southwest, southeast or straight from the south, it will "pop up" over the runway. A construction on those slopes might help, but I'm not sure if it needs to be a wall. $\endgroup$
    – MSalters
    Commented Jun 19, 2018 at 22:13

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It's a completely different problem, and I'm afraid something like that would make the wind shear close to the ground actually worse since it is inhibiting air flow within 200 ft of the ground while the wind just above is unaffected.

Plus the additional turbulence created by those thingamajigs sticking up. Most pilots know how unpleasant it can be trying to land on a runway with a stand of tall trees adjacent to it, with the wind shadow and burble generated by the trees.

The windshear problem for aircraft isn't the wind velocity itself, it's the sudden changes in horizontal velocity at certain levels, which in a large aircraft with a lot of mass, creates large airspeed fluctuations as you climb or descend through, along with vertical flows caused by mountainous terrain can can generate high sink rates that, because of the mass, are slow to be addressed with power. None of that would be helped by a surface barrier. All the barrier would do is create an extra nasty shear + turbulence right at 200 ft.

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