How much turbulence is too much?

In reviewing the Warrior II's performance numbers in preparation for my
recent trip across California, I realized that Va would be much lower than I
had always considered it (given that it's just me inside, with gas burning
off towards reserve only). The Va that's written on my lapboard is 111
KIAS, however that's figured at gross weight (2325 lbs). It goes down all
the way to 88 KIAS (at 1531 lbs.), so I was surprised to see how slow I need
to go, according to normal procedures, when it gets turbulent in the Warrior
(e.g., I should slow down to mid-90's)!

-----------
(from the Warrior's POH, sec. 4.37: "Turbulent Air Operation"):
"In keeping with good operating practice used in all aircraft, it is
recommended that when turbulent air is encountered or expected, the airspeed
be reduced to maneuvering speed to reduce the structural loads caused by
gusts and to allow for inadvertent speed build-ups which may occur as a
result of the turbulence or of distractions caused by the conditions."
-----------

I specifically note this POH's references to "good operating practice used
in all aircraft" and "the structural loads caused by gusts" as they relate
to another question (of turbulence causing increased airframe stress) on
this thread.


"David Megginson" wrote in message
...
Ray Andraka writes:

How does one know if the turbulence is great enough that you should
slow down to Va to keep from structurally damaging the airplane?

If you have to ask, slow down.

Seriously, if I'm just bumping a bit (light chop), I don't worry. If
I'm actually getting uncommanded altitude or orientation changes
(i.e. a sudden 10-degree bank, or a sudden 200 foot altitude change),
I slow down to Va.

I also use some common sense. If I'm flying at 2500 ft AGL under a
clear sky in the afternoon (in the flatlands), I know it's just
thermals and a bit of mechanical turbulence: no big deal. If I'm
flying under cumuloform clouds and they're starting to build (and
there's reported ACC, TCU or CB), I assume that the turbulence could
get bad without warning, so I slow down as soon as I start bouncing
around.


All the best,


David

--
David Megginson, , http://www.megginson.com/

"Marty Ross" wrote in message
news
In reviewing the Warrior II's performance numbers in preparation for my
recent trip across California, I realized that Va would be much lower than
I
had always considered it (given that it's just me inside, with gas burning
off towards reserve only). The Va that's written on my lapboard is 111
KIAS, however that's figured at gross weight (2325 lbs). It goes down all
the way to 88 KIAS (at 1531 lbs.), so I was surprised to see how slow I
need
to go, according to normal procedures, when it gets turbulent in the
Warrior
(e.g., I should slow down to mid-90's)!

Yup. One reason the W&B (or at least the W) is important, even if you know
you're well within bounds, is so you can estimate the Va that corresponds to
your payload. I make sure to have the flight's Va written on my kneeboard
notepad.

--Gary


-----------
(from the Warrior's POH, sec. 4.37: "Turbulent Air Operation"):
"In keeping with good operating practice used in all aircraft, it is
recommended that when turbulent air is encountered or expected, the
airspeed
be reduced to maneuvering speed to reduce the structural loads caused by
gusts and to allow for inadvertent speed build-ups which may occur as a
result of the turbulence or of distractions caused by the conditions."
-----------

I specifically note this POH's references to "good operating practice used
in all aircraft" and "the structural loads caused by gusts" as they relate
to another question (of turbulence causing increased airframe stress) on
this thread.


"David Megginson" wrote in message
...
Ray Andraka writes:

How does one know if the turbulence is great enough that you should
slow down to Va to keep from structurally damaging the airplane?

If you have to ask, slow down.

Seriously, if I'm just bumping a bit (light chop), I don't worry. If
I'm actually getting uncommanded altitude or orientation changes
(i.e. a sudden 10-degree bank, or a sudden 200 foot altitude change),
I slow down to Va.

I also use some common sense. If I'm flying at 2500 ft AGL under a
clear sky in the afternoon (in the flatlands), I know it's just
thermals and a bit of mechanical turbulence: no big deal. If I'm
flying under cumuloform clouds and they're starting to build (and
there's reported ACC, TCU or CB), I assume that the turbulence could
get bad without warning, so I slow down as soon as I start bouncing
around.


All the best,


David

--
David Megginson, , http://www.megginson.com/

Ray Andraka writes:
How does one know if the turbulence is great enough that you
should slow down to Va to keep from structurally damaging the
airplane?

"David Megginson" wrote
If you have to ask, slow down.

"Marty Ross" wrote
In reviewing the Warrior II's performance numbers in preparation
for my recent trip across California, I realized that Va would
be much lower than I had always considered it (given that it's
just me inside, with gas burning off towards reserve only). The
Va that's written on my lapboard is 111 KIAS, however that's
figured at gross weight (2325 lbs). It goes down all the way to
88 KIAS (at 1531 lbs.), so I was surprised to see how slow I
need to go, according to normal procedures, when it gets
turbulent in the Warrior (e.g., I should slow down to mid-90's)!

Somehow I thought that the speed for maximum gust intensity was
Vb, not Va. Is Vb not the top of the "green arc"?
Va means "acceleration loads" as in pilot induced loads through the
use of the a/c controls.
Vb means "gust loads" as in weather induced loads.

Are pilots slowing un-necessarily?

From FAR Part 1:
VB means design speed for maximum gust intensity

From FAR Part 23:
Section 23.341: Gust loads factors.
(a) Each airplane must be designed to withstand loads on each
lifting surface resulting from gusts specified in §23.333(c).
(d) Design speed for maximum gust intensity, VB. For VB, the
following apply:
(1) VB may not be less than the speed determined by the
intersection of the line representing the maximum positive lift,
CNMAX, and the line representing the rough air gust velocity on
the gust V-n diagram, or VS1vng, whichever is less, whe

"Marty Ross" wrote
I specifically note this POH's references to "good operating
practice used in all aircraft" and "the structural loads caused
by gusts" as they relate to another question (of turbulence
causing increased airframe stress) on this thread.

Despite what the POH states, this is not the procedure used in
all aircraft.

Bob Moore
ATP CFI

I've never seen or heard of Vb being published for light aircraft.

Mike
MU-2


"Robert Moore" wrote in message
. 8...
Ray Andraka writes:
How does one know if the turbulence is great enough that you
should slow down to Va to keep from structurally damaging the
airplane?

"David Megginson" wrote
If you have to ask, slow down.

"Marty Ross" wrote
In reviewing the Warrior II's performance numbers in preparation
for my recent trip across California, I realized that Va would
be much lower than I had always considered it (given that it's
just me inside, with gas burning off towards reserve only). The
Va that's written on my lapboard is 111 KIAS, however that's
figured at gross weight (2325 lbs). It goes down all the way to
88 KIAS (at 1531 lbs.), so I was surprised to see how slow I
need to go, according to normal procedures, when it gets
turbulent in the Warrior (e.g., I should slow down to mid-90's)!

Somehow I thought that the speed for maximum gust intensity was
Vb, not Va. Is Vb not the top of the "green arc"?
Va means "acceleration loads" as in pilot induced loads through the
use of the a/c controls.
Vb means "gust loads" as in weather induced loads.

Are pilots slowing un-necessarily?

From FAR Part 1:
VB means design speed for maximum gust intensity

From FAR Part 23:
Section 23.341: Gust loads factors.
(a) Each airplane must be designed to withstand loads on each
lifting surface resulting from gusts specified in §23.333(c).
(d) Design speed for maximum gust intensity, VB. For VB, the
following apply:
(1) VB may not be less than the speed determined by the
intersection of the line representing the maximum positive lift,
CNMAX, and the line representing the rough air gust velocity on
the gust V-n diagram, or VS1vng, whichever is less, whe

"Marty Ross" wrote
I specifically note this POH's references to "good operating
practice used in all aircraft" and "the structural loads caused
by gusts" as they relate to another question (of turbulence
causing increased airframe stress) on this thread.

Despite what the POH states, this is not the procedure used in
all aircraft.

Bob Moore
ATP CFI