Crosswinds & Obstacles are a funny thing

I'm always puzzled by the impact obstacles (trees, buildings, etc) have on a
crosswind.

On the day ten years ago when I earned my tailwheel endorsement, there was a
15 knot direct crosswind above the treeline. But, the field was buried in a
small gap between 75' trees and the crosswind effectively disappeared once
the airplane descended below the trees. Even better, there was no
turbulence. I'm still surprised at how easy it was to land in those
conditions.

As opposed to yesterday, when I was landing at a nearby field in a 10 knot,
60 degree crosswind. There was a row of 50' trees a hundred and fifty feet
upwind of the runway, and those trees (presumably) created a nasty burble at
groundlevel.

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting) landing?
I'm still trying to crack the code on this one...

Thoughts?

KB

Kyle Boatright wrote:
I'm always puzzled by the impact obstacles (trees, buildings, etc) have on a
crosswind.

On the day ten years ago when I earned my tailwheel endorsement, there was a
15 knot direct crosswind above the treeline. But, the field was buried in a
small gap between 75' trees and the crosswind effectively disappeared once
the airplane descended below the trees. Even better, there was no
turbulence. I'm still surprised at how easy it was to land in those
conditions.

As opposed to yesterday, when I was landing at a nearby field in a 10 knot,
60 degree crosswind. There was a row of 50' trees a hundred and fifty feet
upwind of the runway, and those trees (presumably) created a nasty burble at
groundlevel.

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting) landing?
I'm still trying to crack the code on this one...

Thoughts?

KB




Hi KB;

The way I've always handled this and taught others to handle it is NEVER
to fly ANY approach based entirely on expected wind conditions. I know
this sounds over simplistic on the face of it, but you'd be surprised
how many pilots get a handle on wind somewhere between the base turn and
final and get mentally nailed into that wind mindset. The result can
easily be over concentration on an expected wind direction down through
the approach. Then a sudden gust or wind change catches you napping. The
result of that is a second or two DELAY in reaction time to the change.
Usually it comes out ok, but if a pilot gets caught at exactly the wrong
instant (usually down low just before the flare or entering the flare)
that two second delay can suddenly become a potentially serious affair.

What I like to instill in the pilots I train (in my case have trained
:-) is what I call a non committal mindset for wind on the approach.
Loosely explained, this simply amounts to a pilot developing a habit
pattern that digests wind data as received, and begins the approach with
that data in mind, but instead of thinking of wind direction, I like
pilots to think wind CONTROL.
By thinking aircraft control as opposed to expected wind, what happens
is that you are mentally and physically a bit more "loose" on the
approach because you're not expecting a specific wind correction; you
are correcting for what's HAPPENING NOW all through the approach.
Basically it's nothing more than a slight change in the way a pilot
THINKS and FLIES the approach. You're cutting into that 2 second
reaction time because now you're flying the approach as though the winds
were unexpected instead of expected. You have nothing to lose and
everything to gain by using this mindset. If the winds are as expected,
you're automatically correcting for them. But if you get nailed, you're
loose and expecting that as well!!
DH

--
Dudley Henriques

"Kyle Boatright" wrote in
news
I'm always puzzled by the impact obstacles (trees, buildings, etc)
have on a crosswind.

On the day ten years ago when I earned my tailwheel endorsement, there
was a 15 knot direct crosswind above the treeline. But, the field was
buried in a small gap between 75' trees and the crosswind effectively
disappeared once the airplane descended below the trees. Even better,
there was no turbulence. I'm still surprised at how easy it was to
land in those conditions.

As opposed to yesterday, when I was landing at a nearby field in a 10
knot, 60 degree crosswind. There was a row of 50' trees a hundred and
fifty feet upwind of the runway, and those trees (presumably) created
a nasty burble at groundlevel.

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is
it better to bet on an obstacle reducing the crosswind, or is that
obstacle likely to cause a burble that will result in a rotten (or
exciting) landing? I'm still trying to crack the code on this one...



Depends, and it's hard to predict. I know of an airport that spend tens of
thousands on determining whether a new hangar would have a detrimental
effect on a nearby runway threshold. Wind tunnel tests, slide ules. they
built it and it's a nasty approach when the wind is coming that way.


Don't think so much. Do what needs to be done as it needs to be done.
Period.

Bertie

Kyle Boatright wrote:
I'm always puzzled by the impact obstacles (trees, buildings, etc) have on a
crosswind.

On the day ten years ago when I earned my tailwheel endorsement, there was a
15 knot direct crosswind above the treeline. But, the field was buried in a
small gap between 75' trees and the crosswind effectively disappeared once
the airplane descended below the trees. Even better, there was no
turbulence. I'm still surprised at how easy it was to land in those
conditions.

As opposed to yesterday, when I was landing at a nearby field in a 10 knot,
60 degree crosswind. There was a row of 50' trees a hundred and fifty feet
upwind of the runway, and those trees (presumably) created a nasty burble at
groundlevel.

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting) landing?
I'm still trying to crack the code on this one...

Thoughts?

KB

When the winds are just right, the 4 windsocks at my home airport
will be pointing in 4 different directions and there will be an
updraft about half way down the runway.

Trying to guess where the wind is blowing at any given point at any
given time is an exercise in futility.

The center line on the runway is there for a reason.

--
Jim Pennino

Remove .spam.sux to reply.

Interesting runway environment... no trees.. but when the cross winds get
nasty here we get mechanical turbulence on final from the multi story hotel
about 1/2 mile to the offset to final.. clear that and the burble goes away
and just deal with the decreasing performance crosswind as you get closer to
the ground.
BUT !!
The runway is slightly elevated above the drainage ditch between the two
runways.. more of an easy swale than a ditch.. and the low level breeze can
create "ridge lift" in glider pilot language.. as it comes up the swale to
the runway.. low level lift right over the runway.. and you find yourself
with the power back.. wing low crosswind approach and "soaring in ridge lift
and climbing".. with the tire looking at the terra firma only mere inches
below.

The "code to be cracked"?
NEVER EVER stop flying the airplane.. tail wheel or nose tragger.. until it
is in the chocks and chained.

I experienced the same "tree line cross wind shear" when I first learned
taildraggin in a J3 more than 25yrs ago on a grassy runway just off the
beach in New Hampshire.
BT

"Kyle Boatright" wrote in message
news
I'm always puzzled by the impact obstacles (trees, buildings, etc) have on
a crosswind.

On the day ten years ago when I earned my tailwheel endorsement, there was
a 15 knot direct crosswind above the treeline. But, the field was buried
in a small gap between 75' trees and the crosswind effectively disappeared
once the airplane descended below the trees. Even better, there was no
turbulence. I'm still surprised at how easy it was to land in those
conditions.

As opposed to yesterday, when I was landing at a nearby field in a 10
knot, 60 degree crosswind. There was a row of 50' trees a hundred and
fifty feet upwind of the runway, and those trees (presumably) created a
nasty burble at groundlevel.

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting)
landing? I'm still trying to crack the code on this one...

Thoughts?

KB

"Dudley Henriques" wrote in message ...
You have nothing to lose and everything to gain by using this mindset. If the winds are as expected, you're
automatically correcting for them. But if you get nailed, you're loose and expecting that as well!!
DH

--
Dudley Henriques

Yes, always keep flying the plane, all the way to the hangar/tiedown. Need to always watch for those little movements
and peg them before they get big...

Blueskies wrote:
"Dudley Henriques" wrote in message ...
You have nothing to lose and everything to gain by using this mindset. If the winds are as expected, you're
automatically correcting for them. But if you get nailed, you're loose and expecting that as well!!
DH

--
Dudley Henriques

Yes, always keep flying the plane, all the way to the hangar/tiedown. Need to always watch for those little movements
and peg them before they get big...


I've often described flying to students as simply the constant solving
of little problems before they become big problems :-))

--
Dudley Henriques

On Tue, 16 Oct 2007 23:41:18 -0400, Dudley Henriques
wrote:

The way I've always handled this and taught others to handle it is NEVER
to fly ANY approach based entirely on expected wind conditions. I know
this sounds over simplistic on the face of it

Great description of how to handle winds. Not simplistic at all, in my
opinion.

Furthermore, it also gets you into the mindset of going elsewhere if the
winds turn out to be more than can be handled by the
pilot/skillset/airplane combination.


--ron

"Dudley Henriques" wrote in message
...
Kyle Boatright wrote:
snip

Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting)
landing? I'm still trying to crack the code on this one...

Thoughts?

KB




Hi KB;

The way I've always handled this and taught others to handle it is NEVER
to fly ANY approach based entirely on expected wind conditions.
big snip of good stuff

--
Dudley Henriques

Agreed 100%, Dudley.

What's your experience along the following line:

This (insert lengthy experience based finding here) seems to be a workable
rule of thumb for picking a good touchdown point for taking advantage or
minimizing the negative impact of local obstacles to the wind.

KB

Kyle Boatright wrote:
"Dudley Henriques" wrote in message
...
Kyle Boatright wrote:
snip
Because of my widely varied experience with obstacles interacting with
crosswinds, I struggle to pick the *best* runway or landing spot. Is it
better to bet on an obstacle reducing the crosswind, or is that obstacle
likely to cause a burble that will result in a rotten (or exciting)
landing? I'm still trying to crack the code on this one...

Thoughts?

KB



Hi KB;

The way I've always handled this and taught others to handle it is NEVER
to fly ANY approach based entirely on expected wind conditions.
big snip of good stuff
--
Dudley Henriques

Agreed 100%, Dudley.

What's your experience along the following line:

This (insert lengthy experience based finding here) seems to be a workable
rule of thumb for picking a good touchdown point for taking advantage or
minimizing the negative impact of local obstacles to the wind.

KB


Not sure exactly what you are asking here. Can you rephrase the question
sans all literary artifice perhaps? :-)

--
Dudley Henriques