User Guide

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Meanwhile, back in the air: keep increasing back pressure
as the airspeed decreases. Right around the bottom of the green
arc, depending on how you have the airplane loaded, one of two
things will happen:
Either way, you’ve “stalled” according to the FAA. In the first
case, there’s been an actual separation of the airflow over the
wings, and the airplane has started to drop. In the second case,
you’ve run out of elevator control; the airflow is at least partly sep-
arated, and you’re not producing enough lift to hold the airplane up
(hence the rapid rate of descent). In addition, in either case, you’ll
have noticed that the airspeed has rapidly decreased quite a bit
more: as the airflow begins to separate, drag increases radically.
NOW WHAT?!
At least you’ve noticed that the airplane merely sinks - it
doesn’t “plummet” (at least the very docile 172 won’t). Still, if this
sinking isn’t arrested before you reach the ground, it’ll be unfor-
tunate. To recover, all we have to do is to reduce the angle of
attack so the airflow reattaches to the wing, and we do that by
reducing back pressure. Notice that unless you’re in an extreme
situation, you don’t need to shove the yoke all the way forward;
if you do, you’ll certainly un-stall the airplane, but you’ll also
plaster your passengers onto the ceiling and lose a lot of unnec-
essary altitude.
Just lower the nose a bit below the horizon; at the same time,
open the throttle all the way. Hold the nose on the horizon as the
airplane flies out of the stall. Don’t try to pull up again; you’re still
at a low speed and high angle of attack, so a secondary stall isn’t
far away.
THE EASY ONE FIRST
Get the airplane trimmed up for a normal cruise and make
your clearing turns. When you’re recovered to straight and level
flight, ease the power back to idle. The nose will try to drop, but
don’t let it. Instead, bring it up above the horizon about ten
degrees; what we’re looking for is a gradual and constant slowing,
with the airspeed ideally reducing by one knot per second.
You’ll notice that as the airplane slows, it takes more and
more back pressure to hold the pitch attitude. Glance at the air-
speed indicator. As it reaches a point 5 to 8 knots above the bot-
tom of the green arc (the flaps-up level stalling speed at maximum
weight), you’ll start to hear a mournful whine.
This isn’t your passengers (actually, it might be). Built into
the root of the left wing is a little air horn, plumbed to an opening
in the wing’s leading edge. In normal flight, the opening senses nor-
mal, or even higher than normal, air pressure. As the angle of attack
increases, however, the stagnation point - the point on the leading
edge at which the air splits to go above and below the wing - moves
downward. Just before stalling angle of attack, it’s moved far
enough that the opening is now on the upper, or low-pressure, side
of the stagnation point. Air is sucked out through the horn, and
that’s the stall warning sound you hear. It’s a simple, reliable system,
requiring no electricity or moving parts.
In fact, if you’re tall, you can check it during preflight
inspection by placing your mouth over the opening and sucking
gently; you’ll hear the horn. An instructor of my acquaintance
used to suck so hard that he’d damage the horns until a mechan-
ic prepared an airplane with a few squirts of Tabasco just inside
the opening…
1. The airplane will give a little shudder and its nose will
drop a foot or so; a wing may drop a bit as well. You’ll
feel a definite “sinking sensation.”
2. (More likely): You’ll “run out of stick”—you’ll have the
yoke as back as far as it will go. The airplane will sort of
tiredly ease its nose back down to the horizon, possibly
with a bit of shuddering and shaking, and the VSI will
show a rapid descent.
Flight Instruction
Flight Instruction
Full Stall