Flight Training - May 2015 - 45

WHAT IS AWOS?
One student pilot recalls her suspicion
of wind being both caused and cured by
AWOS-automatic weather observation
systems). While still fearful, the first thing
she'd do before showing up for a lesson was
to call AWOS and get the wind speed. If
reported at a certain level, she'd start figuring out ways to get out of flying. Later, when
she'd tamed her fear and made peace with
the wind, AWOS was her friend. Consisting
of various sensors, a processor, a computergenerated voice system, and transmitter,
these stations broadcast minute-by-minute,
real-time local weather information.
Frequencies for AWOS may be found near
the airport data on the sectional chart.

>> There are four basic levels of AWOS:
AWOS-A. Reports only altimeter settings.
AWOS-1. Usually reports altimeter setting,
wind data, temperature, dew point, and
density altitude.
AWOS-2. Provides the information provided
by AWOS-1 plus visibility.
AWOS-3. Provides the information provided
by AWOS-2 plus cloud-ceiling data.

is no big deal. However, the fear factor
associated with 30 degrees off heading is
much more than at 15 degrees. At 45 to 60
degrees, the fear meter is nearly pegged.
Ninety degrees? Forget it! Even though
the concern raised by that seemingly fearsome angle is generally unfounded, far too
many pilots won't challenge a wind at 90
degrees, almost regardless of its strength.
And this is unfortunate.
Most certified aircraft have a maximum demonstrated 90-degree crosswind
component published in the pilot's
operating handbook. However, like many
things in aviation, it's not an absolute.
We don't know what the actual limiting
number is, but we do know one fact: The
number in the POH or placarded on the
panel is achievable for the average pilot-
or the manufacturer wouldn't go out on a
limb and say so.

There is, however, something about direction that is critical, and that
is handling a wind that is slightly behind the wing. A tailwind of any kind
adds to our groundspeed, and a quartering tailwind can have us really
whistling on touchdown. But, that's not the real problem. The real difficulties come from the fact that a quartering tailwind changes the airplane's
feel. It's no longer solid and reacting to the controls in the way that you're
accustomed. As long as you trust your eyes and react to what you're seeing, as opposed to what you're feeling, you'll be doing the right thing.
GUST SPREAD. The gust spread is what makes any wind-but especially
a crosswind-potentially dangerous. It must be carefully analyzed before
takeoff and during the approach to the airport. The gust spread can take
both the wind direction and velocity and combine them in such a way that
they can become exceptionally challenging.
All significant gust spreads should command respect, but the gusts that
are the most worrisome are those that change direction as they gust. The
main wind may be at 20 degrees to the runway, but the gusts are coming
from 50 degrees to the runway. If they are the kind of gusts that are very
sharp in nature, as indicated by the windsock's snapping and whipping as
it changes direction, they can cause lots of heartburn in the flare:
Not only do they increase the crosswind correction needed for an instant
or two, but they change the wind the aircraft is feeling on the nose,
which can cause the aircraft to balloon-or cause it to fall when the
gust dies.
The gusts that can absolutely eat an airplane are those that, when
they snap around, instantly take the wind from in front of the wing tip to
behind it. In that situation a headwind instantly becomes a tailwind, and
it's not uncommon for an aircraft to suddenly fall out of the air in those
conditions. It has the same effect as wind shear-which, in some ways, it
is. Treat this kind of wind with care and, if flying a taildragger, just don't
take off or land. Quartering tailwinds and taildraggers shouldn't be mixed.
If caught in one, tell either the tower or unicom that you consider the
wind to be dangerous and you're going to use another runway-even if
doing so requires you to land at a different airport.
WHEN THE RUBBER MEETS THE RUNWAY. There are no wind indicators of
any kind that are close enough to our airplane to tell us exactly what the
wind is doing every moment. So, when it comes to controlling wind, we
take under advisement the indications that the windsock and trees provide-but we don't hang our hat on them. We trust only what the airplane
is telling us directly, what it is experiencing at that exact moment, and
correct accordingly. If the airplane isn't doing what we want it to do, we
do whatever is needed to make it go where we want it to go, regardless of
what a windsock or control tower tells us. It comes back to the old axiom,
"Fly the airplane."
Also remember that the goal in aviating is to touch down at the minimum speed and carry as little energy as possible onto the ground. The
slower you're moving, the less energy there is to control. Any headwind at
all helps cut down the energy that's associated with your speed. So, wind
is your friend-really, it is!
Budd Davisson is an aviation writer/photographer and magazine editor. A CFI since 1967,
he teaches about 30 hours a month in his Pitts S-2A. Visit his website (www.airbum.com).

MAY 2015 FLIGHT TRAINING

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