Flight Training - June 2014 - 49

INSTRUCTOR REPORT

More bang for the bank
The value of turns around a point
» By Rod Machado

WHILE FLYING ABOVE a grove of
oak trees, I asked my student Bob
to perform turns around a point.
During the downwind turn, he
drifted away from his starting
point, a big oak tree. What happened next surprised me. Bob
went out on a limb and continued
the maneuver around another,
similar-looking tree-hoping that I
wouldn't notice. Silly Bob.
Turns around a point is my
favorite ground reference maneuver, even when Bob does it. Some
instructors prefer eights around
pylons or S-turns across a road,
but I'll take this maneuver for its
practical value and educational
potential, any day.
The FAA says the maneuver
helps students develop their subconscious control of an airplane
and deepens their understanding
of the relationship between bank
angle and turn radius, and wind
drift correction, while turning.
The FAA says that the maneuver is a "logical extension" of
S-turns across a road. Nevertheless, I always introduce S-turns
across a road after turns around a
point. Why? Unless your student
is named Euclid, it's difficult
to maintain a turn radius that
produces an authentic half-circle
without having a specific pivot
point about which to turn. Evaluating the resultant half-circles for
geometric accuracy often seems
highly subjective (unless your
student is named "Bob" and an oak
tree is involved).
Turns around a point are
equally important for reasons
the FAA doesn't discuss. It turns
out this maneuver is a powerful
myth buster if taught correctly.
I'm speaking of the downwind

turn myth. This is a longstanding aviation myth that suggests a
downwind turn (from a headwind
to a tailwind) might cause the airplane to stall from a loss of wind
speed over the wings. Believing
this is similar to believing that
putting hand lotion in your fuel
tank will make your landings
smoother, softer, and younger
looking. To set the record straight,
turning with the wind doesn't
rob the wings of airspeed. Turns
around a point debunk this myth
empirically.
Performing turns around a
point in any wind requires always
turning from upwind to down-

a decrease in indicated airspeed.
Learning to limit oneself to 45
degrees of bank (the maximum
permitted by this maneuver) helps
protect against low-altitude accelerated stalls.
Controlling the bank angle and
airspeed also help to minimize the
effects of the perceptual illusion
the student might experience
when turning downwind. As the
airplane turns with the wind, its
increasing groundspeed results in
the terrain moving faster relative
to the side window frame. This
creates the illusion that the airplane is approaching the surface
(i.e., losing altitude). Without a

TO SET THE RECORD STRAIGHT, TURNING WITH THE WIND DOESN'T
ROB THE WINGS OF AIRSPEED. TURNS AROUND A POINT DEBUNK
THIS MYTH EMPIRICALLY.
wind during the maneuver. The
airplane, however, never experiences a loss of airspeed as a result
of the airplane moving with the
wind. It is true that the effects
of wind shear and perceptual
illusions might cause the wing to
stall when turning downwind, but
not the downwind turn itself. The
revelation here is that an airplane's
changing groundspeed has no
effect on the lift produced by
the wings.
Turns around a point also can
teach the student to be cognizant
of the bank angle and airspeed as
she maneuvers around any ground
reference. Turning downwind
during this maneuver requires
an increase in bank angle and a
commensurate increase in angle
of attack to hold altitude. With
the power constant, this results in
an increase in induced drag and

trained counter response, the student might instinctually pull aft on
the yoke, which steepens the bank
and reduces the airspeed. For the
unwary, the result often is a lowaltitude accelerated stall. Turns
around a point help the student
to properly interpret the meaning
of accelerating ground movement
while countering the instinctual
response to pull aft on the yoke in
a downwind turn.
Aside from the FAA's stated
benefits of teaching turns around a
point, you now have two additional "hidden" reasons supporting
this maneuver's training value. In
my book, that's a lot of bang for
your bank angle.
Rod Machado is a flight instructor, author,
educator, and speaker. He has been a pilot
since 1970 and a CFI since 1973.
Visit his blog (www.rodmachado.com).

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