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More lift
Additional
induced drag
Rudder overcomes
adverse yaw to
coordinate the turn
Reduced lift
Figure 3-7. Forces during a turn.
Ch 03.qxd 7/13/04 11:08 AM Page 3-8
3-9
to become slower. [Figure 3-9 on next page] Therefore,
at a given angle of bank, a higher true airspeed will
make the radius of turn larger because the airplane will
be turning at a slower rate.
When changing from a shallow bank to a medium
bank, the airspeed of the wing on the outside of the turn
increases in relation to the inside wing as the radius of
turn decreases. The additional lift developed because
of this increase in speed of the wing balances the
inherent lateral stability of the airplane. At any given
airspeed, aileron pressure is not required to maintain
the bank. If the bank is allowed to increase from a
medium to a steep bank, the radius of turn decreases
further. The lift of the outside wing causes the bank to
steepen and opposite aileron is necessary to keep the
bank constant.
As the radius of the turn becomes smaller, a significant
difference develops between the speed of the inside
wing and the speed of the outside wing. The wing on
the outside of the turn travels a longer circuit than the
inside wing, yet both complete their respective circuits
in the same length of time. Therefore, the outside wing
travels faster than the inside wing, and as a result, it
develops more lift. This creates an overbanking
tendency that must be controlled by the use of the
ailerons. [Figure 3-10] Because the outboard wing is
developing more lift, it also has more induced drag.
This causes a slight slip during steep turns that must be
corrected by use of the rudder.
Sometimes during early training in steep turns, the
nose may be allowed to get excessively low resulting
in a significant loss in altitude. To recover, the pilot
should first reduce the angle of bank with coordinated
use of the rudder and aileron, then raise the nose of the
airplane to level flight with the elevator. If recovery
from an excessively nose-low steep bank condition is
attempted by use of the elevator only, it will cause a
steepening of the bank and could result in overstressing
the airplane. Normally, small corrections for pitch
during steep turns are accomplished with the elevator,
and the bank is held constant with the ailerons.
To establish the desired angle of bank, the pilot should
use outside visual reference points, as well as the bank
indicator on the attitude indicator.
The best outside reference for establishing the degree of
bank is the angle formed by the raised wing of low-wing
airplanes (the lowered wing of high-wing airplanes) and
the horizon, or the angle made by the top of the engine
cowling and the horizon. [Figure 3-11 on page 3-11]
Since on most light airplanes the engine cowling is fairly
flat, its horizontal angle to the horizon will give some
indication of the approximate degree of bank. Also,
information obtained from the attitude indicator will
show the angle of the wing in relation to the horizon.
Information from the turn coordinator, however, will not.
SKID COORDINATED SLIP
TURN
Pilot feels
sideways force
to outside of turn
Pilot feels
force straight
down into seat
Pilot feels
sideways force
to inside of turn
Ball to outside
of turn
Ball centered Ball to inside
of turn
Figure 3-8. Indications of a slip and skid.
OVERBANKING TENDENCY
Outer wing travels greater distance
• Higher Speed
• More Lift
Inner wing travels shorter distance
• Lower speed
• Less lift
Figure 3-10. Overbanking tendency during a steep turn.
Ch 03.qxd 7/13/04 11:08 AM Page 3-9
3-10
CONSTANT AIRSPEED
10° Angle of Bank
20° Angle of Bank
30° Angle of Bank
When airspeed is
held constant, a
larger angle of bank
will result in a
smaller turn radius
and a greater turn
rate.
CONSTANT ANGLE OF BANK
When angle of bank
is held constant, a
slower airspeed will
result in a smaller
turn radius and
greater turn rate.
80 kts
90 kts
100 kts
Figure 3-9. Angle of bank and airspeed regulate rate and radius of turn.
Ch 03.qxd 7/13/04 11:08 AM Page 3-10
3-11
The pilot’s posture while seated in the airplane is very
important, particularly during turns. It will affect the
interpretation of outside visual references. At the
beginning, the student may lean away from the turn in
an attempt to remain upright in relation to the ground
rather than ride with the airplane. This should be corrected
immediately if the student is to properly learn to
use visual references. [Figure 3-12]
Parallax error is common among students and experienced
pilots. This error is a characteristic of airplanes
that have side-by-side seats because the pilot is seated to
one side of the longitudinal axis about which the airplane
rolls. This makes the nose appear to rise when making a
left turn and to descend when making right turns. [Figure
3-13]
Beginning students should not use large aileron and
rudder applications because this produces a rapid roll
rate and allows little time for corrections before the
desired bank is reached. Slower (small control displacement)
roll rates provide more time to make
necessary pitch and bank corrections. As soon as
the airplane rolls from the wings-level attitude, the
nose should also start to move along the horizon,
increasing its rate of travel proportionately as the
bank is increased.
The following variations provide excellent guides.
• If the nose starts to move before the bank starts,
rudder is being applied too soon.
• If the bank starts before the nose starts turning, or
the nose moves in the opposite direction, the rudder
is being applied too late.
• If the nose moves up or down when entering a
bank, excessive or insufficient up elevator is being
applied.
As the desired angle of bank is established, aileron
and rudder pressures should be relaxed. This will
stop the bank from increasing because the aileron
and rudder control surfaces will be neutral in their
streamlined position. The up-elevator pressure
should not be relaxed, but should be held constant to
maintain a constant altitude. Throughout the turn, the
pilot should cross-check the airspeed indicator, and
if the airspeed has decreased more than 5 knots, additional
power should be used. The cross-check should
also include outside references, altimeter, and vertical
speed indicator (VSI), which can help determine
whether or not the pitch attitude is correct. If gaining
or losing altitude, the pitch attitude should be
adjusted in relation to the horizon, and then the
altimeter and VSI rechecked to determine if altitude
is being maintained.
Figure 3-11. Visual reference for angle of bank.
RIGHT WRONG
Figure 3-13. Parallax view.
Figure 3-12. Right and wrong posture while seated in the
airplane.
Ch 03.qxd 7/13/04 11:08 AM Page 3-11
3-12
During all turns, the ailerons, rudder, and elevator are
used to correct minor variations in pitch and bank just
as they are in straight-and-level flight.
The rollout from a turn is similar to the roll-in except
the flight controls are applied in the opposite direction.
Aileron and rudder are applied in the direction of the
rollout or toward the high wing. As the angle of bank
decreases, the elevator pressure should be relaxed as
necessary to maintain altitude.
Since the airplane will continue turning as long as there
is any bank, the rollout must be started before reaching
the desired heading. The amount of lead required to roll
out on the desired heading will depend on the degree of
bank used in the turn. Normally, the lead is one-half the
degrees of bank. For example, if the bank is 30°, lead the
rollout by 15°. As the wings become level, the control
pressures should be smoothly relaxed so that the controls
are neutralized as the airplane returns to straight-andlevel
flight. As the rollout is being completed, attention
should be given to outside visual references, as well as
the attitude and heading indicators to determine that the
wings are being leveled and the turn stopped.
Instruction in level turns should begin with medium
turns, so that the student has an opportunity to grasp
the fundamentals of turning flight without having
to deal with overbanking tendency, or the inherent
stability of the airplane attempting to level the
wings. The instructor should not ask the student to
roll the airplane from bank to bank, but to change
its attitude from level to bank, bank to level, and so
on with a slight pause at the termination of each
phase. This pause allows the airplane to free itself
from the effects of any misuse of the controls and
assures a correct start for the next turn. During
these exercises, the idea of control forces, rather
than movement, should be emphasized by pointing
out the resistance of the controls to varying forces
applied to them. The beginning student should be
encouraged to use the rudder freely. Skidding in this
phase indicates positive control use, and may be
easily corrected later. The use of too little rudder, or
rudder use in the wrong direction at this stage of
training, on the other hand, indicates a lack of
proper conception of coordination.
In practicing turns, the action of the airplane’s nose
will show any error in coordination of the controls.
Often, during the entry or recovery from a bank, the
nose will describe a vertical arc above or below the
horizon, and then remain in proper position after the
bank is established. This is the result of lack of timing
and coordination of forces on the elevator and rudder
controls during the entry and recovery. It indicates that
the student has a knowledge of correct turns, but that
entry and recovery techniques are in error.
Because the elevator and ailerons are on one control,
and pressures on both are executed simultaneously, the
beginning pilot is often apt to continue pressure on one
of these unintentionally when force on the other only
is intended. This is particularly true in left-hand turns,
because the position of the hands makes correct
movements slightly awkward at first. This is sometimes
responsible for the habit of climbing slightly in
right-hand turns and diving slightly in left-hand
turns. This results from many factors, including the
unequal rudder pressures required to the right and to
the left when turning, due to the torque effect.
The tendency to climb in right-hand turns and descend
in left-hand turns is also prevalent in airplanes having
side-by-side cockpit seating. In this case, it is due to
the pilot’s being seated to one side of the longitudinal
axis about which the airplane rolls. This makes the
nose appear to rise during a correctly executed left turn
and to descend during a correctly executed right turn.
An attempt to keep the nose on the same apparent level
will cause climbing in right turns and diving in left
turns.
Excellent coordination and timing of all the controls in
turning requires much practice. It is essential that this
coordination be developed, because it is the very basis
of this fundamental flight maneuver.
If the body is properly relaxed, it will act as a pendulum
and may be swayed by any force acting on it.
During a skid, it will be swayed away from the turn,
and during a slip, toward the inside of the turn. The
same effects will be noted in tendencies to slide on the
seat. As the “feel” of flying develops, the properly
directed student will become highly sensitive to this
last tendency and will be able to detect the presence
of, or even the approach of, a slip or skid long before
any other indication is present.
Common errors in the performance of level turns are:
• Failure to adequately clear the area before beginning
the turn.
• Attempting to execute the turn solely by instrument
reference.
• Attempting to sit up straight, in relation to the
ground, during a turn, rather than riding with the
airplane.
• Insufficient feel for the airplane as evidenced by
the inability to detect slips/skids without reference
to flight instruments.
• Attempting to maintain a constant bank angle by
referencing the “cant” of the airplane’s nose.
Ch 03.qxd 7/13/04 11:08 AM Page 3-12
3-13
• Fixating on the nose reference while excluding
wingtip reference.
• “Ground shyness”—making “flat turns” (skidding)
while operating at low altitudes in a conscious
or subconscious effort to avoid banking
close to the ground.
• Holding rudder in the turn.
• Gaining proficiency in turns in only one direction
(usually the left).
• Failure to coordinate the use of throttle with other
controls.
• Altitude gain/loss during the turn.
CLIMBS AND CLIMBING TURNS
When an airplane enters a climb, it changes its flightpath
from level flight to an inclined plane or climb
attitude. In a climb, weight no longer acts in a direction
perpendicular to the flightpath. It acts in a rearward
direction. This causes an increase in total drag
requiring an increase in thrust (power) to balance the
forces. An airplane can only sustain a climb angle
when there is sufficient thrust to offset increased drag;
therefore, climb is limited by the thrust available.
Like other maneuvers, climbs should be performed
using outside visual references and flight instruments.
It is important that the pilot know the engine power
settings and pitch attitudes that will produce the following
conditions of climb.
NORMAL CLIMB—Normal climb is performed at
an airspeed recommended by the airplane manufacturer.
Normal climb speed is generally somewhat
higher than the airplane’s best rate of climb. The additional
airspeed provides better engine cooling, easier
control, and better visibility over the nose. Normal
climb is sometimes referred to as “cruise climb.”
Complex or high performance airplanes may have a
specified cruise climb in addition to normal climb.
BEST RATE OF CLIMB—Best rate of climb (VY) is
performed at an airspeed where the most excess power
is available over that required for level flight. This
condition of climb will produce the most gain in altitude
in the least amount of time (maximum rate of
climb in feet per minute). The best rate of climb made
at full allowable power is a maximum climb. It must
be fully understood that attempts to obtain more
climb performance than the airplane is capable of by
increasing pitch attitude will result in a decrease in
the rate of altitude gain.
BEST ANGLE OF CLIMB—Best angle of climb
(VX) is performed at an airspeed that will produce the
most altitude gain in a given distance. Best angle-ofclimb
airspeed (VX) is considerably lower than best
rate of climb (VY), and is the airspeed where the most
excess thrust is available over that required for level
flight. The best angle of climb will result in a steeper
climb path, although the airplane will take longer to
reach the same altitude than it would at best rate of
climb. The best angle of climb, therefore, is used in
clearing obstacles after takeoff. [Figure 3-14]
It should be noted that, as altitude increases, the speed
for best angle of climb increases, and the speed for best
rate of climb decreases. The point at which these two
speeds meet is the absolute ceiling of the airplane.
[Figure 3-15 on next page]
A straight climb is entered by gently increasing pitch
attitude to a predetermined level using back-elevator
pressure, and simultaneously increasing engine power
to the climb power setting. Due to an increase in
downwash over the horizontal stabilizer as power is
applied, the airplane’s nose will tend to immediately
begin to rise of its own accord to an attitude higher than
Best angle-of-climb airspeed (Vx)
gives the greatest altitude gain in the
shortest horizontal distance.
Best rate-of-climb airspeed (Vy)
gives the greatest altitude gain
in the shortest time.
Figure 3-14. Best angle of climb vs. best rate of climb.
Ch 03.qxd 7/13/04 11:08 AM Page 3-13
3-14
that at which it would stabilize. The pilot must be prepared
for this.
As a climb is started, the airspeed will gradually diminish.
This reduction in airspeed is gradual because of
the initial momentum of the airplane. The thrust
required to maintain straight-and-level flight at a given
airspeed is not sufficient to maintain the same airspeed
in a climb. Climbing flight requires more power than
flying level because of the increased drag caused by
gravity acting rearward. Therefore, power must be
advanced to a higher power setting to offset the
increased drag.
The propeller effects at climb power are a primary factor.
This is because airspeed is significantly slower
than at cruising speed, and the airplane’s angle of
attack is significantly greater. Under these conditions,
torque and asymmetrical loading of the propeller will
cause the airplane to roll and yaw to the left. To
counteract this, the right rudder must be used.
During the early practice of climbs and climbing turns,
this may make coordination of the controls seem awkward
(left climbing turn holding right rudder), but after
a little practice this correction for propeller effects will
become instinctive.
Trim is also a very important consideration during a
climb. After the climb has been established, the airplane
should be trimmed to relieve all pressures from
the flight controls. If changes are made in the pitch attitude,
power, or airspeed, the airplane should be
retrimmed in order to relieve control pressures.
When performing a climb, the power should be
advanced to the climb power recommended by the
manufacturer. If the airplane is equipped with a controllable-
pitch propeller, it will have not only an
engine tachometer, but also a manifold pressure gauge.
Normally, the flaps and landing gear (if retractable)
should be in the retracted position to reduce drag.
As the airplane gains altitude during a climb, the manifold
pressure gauge (if equipped) will indicate a loss
in manifold pressure (power). This is because the same
volume of air going into the engine’s induction system
gradually decreases in density as altitude increases.
When the volume of air in the manifold decreases, it
causes a loss of power. This will occur at the rate of
approximately 1-inch of manifold pressure for each
1,000-foot gain in altitude. During prolonged climbs,
the throttle must be continually advanced, if constant
power is to be maintained.
To enter the climb, simultaneously advance the throttle
and apply back-elevator pressure to raise the nose of the
airplane to the proper position in relation to the horizon.
As power is increased, the airplane’s nose will rise due
to increased download on the stabilizer. This is caused
by increased slipstream. As the pitch attitude increases
and the airspeed decreases, progressively more right
rudder must be applied to compensate for propeller
effects and to hold a constant heading.
After the climb is established, back-elevator pressure
must be maintained to keep the pitch attitude constant.
As the airspeed decreases, the elevators will try to
return to their neutral or streamlined position, and the
airplane’s nose will tend to lower. Nose-up elevator
trim should be used to compensate for this so that the
pitch attitude can be maintained without holding backelevator
pressure. Throughout the climb, since the
power is fixed at the climb power setting, the airspeed
is controlled by the use of elevator.
A cross-check of the airspeed indicator, attitude indicator,
and the position of the airplane’s nose in relation
to the horizon will determine if the pitch attitude is
correct. At the same time, a constant heading should
be held with the wings level if a straight climb is being
performed, or a constant angle of bank and rate of turn
if a climbing turn is being performed. [Figure 3-16]
To return to straight-and-level flight from a climb, it is
necessary to initiate the level-off at approximately 10
percent of the rate of climb. For example, if the airplane
is climbing at 500 feet per minute (f.p.m.), leveling off
should start 50 feet below the desired altitude. The nose
must be lowered gradually because a loss of altitude
will result if the pitch attitude is changed to the level
flight position without allowing the airspeed to increase
proportionately.
Absolute Ceiling
Service Ceiling
Figure 3-15. Absolute ceiling.
Ch 03.qxd 7/13/04 11:08 AM Page 3-14
3-15
After the airplane is established in level flight at a
constant altitude, climb power should be retained
temporarily so that the airplane will accelerate to the
cruise airspeed more rapidly. When the speed reaches
the desired cruise speed, the throttle setting and the
propeller control (if equipped) should be set to the
cruise power setting and the airplane trimmed. After
allowing time for engine temperatures to stabilize,
adjust the mixture control as required.
In the performance of climbing turns, the following
factors should be considered.
• With a constant power setting, the same pitch attitude
and airspeed cannot be maintained in a bank
as in a straight climb due to the increase in the total
lift required.
• The degree of bank should not be too steep. A
steep bank significantly decreases the rate of
climb. The bank should always remain constant.
• It is necessary to maintain a constant airspeed and
constant rate of turn in both right and left turns.
The coordination of all flight controls is a primary
factor.
• At a constant power setting, the airplane will climb
at a slightly shallower climb angle because some
of the lift is being used to turn the airplane.
• Attention should be diverted from fixation on the
airplane’s nose and divided equally among inside
and outside references.
There are two ways to establish a climbing turn. Either
establish a straight climb and then turn, or enter the
climb and turn simultaneously. Climbing turns should
be used when climbing to the local practice area.
Climbing turns allow better visual scanning, and it is
easier for other pilots to see a turning aircraft.
In any turn, the loss of vertical lift and increased
induced drag, due to increased angle of attack,
becomes greater as the angle of bank is increased. So
shallow turns should be used to maintain an efficient
rate of climb.
All the factors that affect the airplane during level
(constant altitude) turns will affect it during climbing
turns or any other training maneuver. It will be noted
that because of the low airspeed, aileron drag (adverse
yaw) will have a more prominent effect than it did in
straight-and-level flight and more rudder pressure will
have to be blended with aileron pressure to keep the
airplane in coordinated flight during changes in bank
angle. Additional elevator back pressure and trim will
also have to be used to compensate for centrifugal
force, for the loss of vertical lift, and to keep pitch attitude
constant.
During climbing turns, as in any turn, the loss of vertical
lift and induced drag due to increased angle of
attack becomes greater as the angle of bank is
increased, so shallow turns should be used to maintain
an efficient rate of climb. If a medium or steep banked
turn is used, climb performance will be degraded.
Common errors in the performance of climbs and
climbing turns are:
• Attempting to establish climb pitch attitude by referencing
the airspeed indicator, resulting in “chasing”
the airspeed.
• Applying elevator pressure too aggressively,
resulting in an excessive climb angle.
• Applying elevator pressure too aggressively during
level-off resulting in negative “G” forces.
• Inadequate or inappropriate rudder pressure during
climbing turns.
• Allowing the airplane to yaw in straight climbs,
usually due to inadequate right rudder pressure.
• Fixation on the nose during straight climbs, resulting
in climbing with one wing low.
• Failure to initiate a climbing turn properly with use
of rudder and elevators, resulting in little turn, but
rather a climb with one wing low.
• Improper coordination resulting in a slip which
counteracts the effect of the climb, resulting in little
or no altitude gain.
• Inability to keep pitch and bank attitude constant
during climbing turns.
• Attempting to exceed the airplane’s climb capability.
DESCENTS AND DESCENDING TURNS
When an airplane enters a descent, it changes its flightpath
from level to an inclined plane. It is important that
Figure 3-16. Climb indications.
Ch 03.qxd 7/13/04 11:08 AM Page 3-15
3-16
the pilot know the power settings and pitch attitudes
that will produce the following conditions of descent.
PARTIAL POWER DESCENT—The normal
method of losing altitude is to descend with partial
power. This is often termed “cruise” or “enroute”
descent. The airspeed and power setting recommended
by the airplane manufacturer for prolonged descent
should be used. The target descent rate should be 400 –
500 f.p.m. The airspeed may vary from cruise airspeed
to that used on the downwind leg of the landing pattern.
But the wide range of possible airspeeds should
not be interpreted to permit erratic pitch changes. The
desired airspeed, pitch attitude, and power combination
should be preselected and kept constant.
DESCENT AT MINIMUM SAFE AIRSPEED—A
minimum safe airspeed descent is a nose-high, power
assisted descent condition principally used for clearing
obstacles during a landing approach to a short runway.
The airspeed used for this descent condition is recommended
by the airplane manufacturer and normally is
no greater than 1.3 VSO. Some characteristics of the
minimum safe airspeed descent are a steeper than normal
descent angle, and the excessive power that may
be required to produce acceleration at low airspeed
should “mushing” and/or an excessive rate of descent
be allowed to develop.
GLIDES—A glide is a basic maneuver in which the
airplane loses altitude in a controlled descent with little
or no engine power; forward motion is maintained by
gravity pulling the airplane along an inclined path and
the descent rate is controlled by the pilot balancing the
forces of gravity and lift.
Although glides are directly related to the practice of
power-off accuracy landings, they have a specific
operational purpose in normal landing approaches, and
forced landings after engine failure. Therefore, it is
necessary that they be performed more subconsciously
than other maneuvers because most of the time during
their execution, the pilot will be giving full attention to
details other than the mechanics of performing the
maneuver. Since glides are usually performed relatively
close to the ground, accuracy of their execution
and the formation of proper technique and habits are of
special importance.
Because the application of controls is somewhat different
in glides than in power-on descents, gliding
maneuvers require the perfection of a technique
somewhat different from that required for ordinary
power-on maneuvers. This control difference is
caused primarily by two factors—the absence of the
usual propeller slipstream, and the difference in the
relative effectiveness of the various control surfaces
at slow speeds.
The glide ratio of an airplane is the distance the airplane
will, with power off, travel forward in relation to
the altitude it loses. For instance, if an airplane travels
10,000 feet forward while descending 1,000 feet, its
glide ratio is said to be 10 to 1.
The glide ratio is affected by all four fundamental
forces that act on an airplane (weight, lift, drag, and
thrust). If all factors affecting the airplane are constant,
the glide ratio will be constant. Although the effect of
wind will not be covered in this section, it is a very
prominent force acting on the gliding distance of the
airplane in relationship to its movement over the
ground. With a tailwind, the airplane will glide farther
because of the higher groundspeed. Conversely, with a
headwind the airplane will not glide as far because of
the slower groundspeed.
Variations in weight do not affect the glide angle provided
the pilot uses the correct airspeed. Since it is the
lift over drag (L/D) ratio that determines the distance the
airplane can glide, weight will not affect the distance.
The glide ratio is based only on the relationship of the
aerodynamic forces acting on the airplane. The only
effect weight has is to vary the time the airplane will
glide. The heavier the airplane the higher the airspeed
must be to obtain the same glide ratio. For example, if
two airplanes having the same L/D ratio, but different
weights, start a glide from the same altitude, the heavier
airplane gliding at a higher airspeed will arrive at the
same touchdown point in a shorter time. Both airplanes
will cover the same distance, only the lighter airplane
will take a longer time.
Under various flight conditions, the drag factor may
change through the operation of the landing gear
and/or flaps. When the landing gear or the flaps are
extended, drag increases and the airspeed will
decrease unless the pitch attitude is lowered. As the
pitch is lowered, the glidepath steepens and reduces
the distance traveled. With the power off, a windmilling
propeller also creates considerable drag,
thereby retarding the airplane’s forward movement.
Although the propeller thrust of the airplane is normally
dependent on the power output of the engine,
the throttle is in the closed position during a glide so
the thrust is constant. Since power is not used during a
glide or power-off approach, the pitch attitude must be
adjusted as necessary to maintain a constant airspeed.
The best speed for the glide is one at which the airplane
will travel the greatest forward distance for a
given loss of altitude in still air. This best glide speed
corresponds to an angle of attack resulting in the least
drag on the airplane and giving the best lift-to-drag
ratio (L/DMAX). [Figure 3-17]
Ch 03.qxd 7/13/04 11:08 AM Page 3-16
3-17
Any change in the gliding airspeed will result in a proportionate
change in glide ratio. Any speed, other than
the best glide speed, results in more drag. Therefore, as
the glide airspeed is reduced or increased from the
optimum or best glide speed, the glide ratio is also
changed. When descending at a speed below the best
glide speed, induced drag increases. When descending
at a speed above best glide speed, parasite drag
increases. In either case, the rate of descent will
increase. [Figure 3-18]
This leads to a cardinal rule of airplane flying that a
student pilot must understand and appreciate: The pilot
must never attempt to “stretch” a glide by applying
back-elevator pressure and reducing the airspeed
below the airplane’s recommended best glide speed.
Attempts to stretch a glide will invariably result in an
increase in the rate and angle of descent and may precipitate
an inadvertent stall.
To enter a glide, the pilot should close the throttle and
advance the propeller (if so equipped) to low pitch
(high r.p.m.). A constant altitude should be held with
back pressure on the elevator control until the airspeed
decreases to the recommended glide speed. Due to a
decrease in downwash over the horizontal stabilizer as
power is reduced, the airplane’s nose will tend to
immediately begin to lower of its own accord to an attitude
lower than that at which it would stabilize. The
pilot must be prepared for this. To keep pitch attitude
constant after a power change, the pilot must counteract
the immediate trim change. If the pitch attitude
is allowed to decrease during glide entry, excess
speed will be carried into the glide and retard the
attainment of the correct glide angle and airspeed.
Speed should be allowed to dissipate before the pitch
attitude is decreased. This point is particularly
important in so-called clean airplanes as they are
very slow to lose their speed and any slight deviation
of the nose downwards results in an immediate
increase in airspeed. Once the airspeed has dissipated
to normal or best glide speed, the pitch attitude
should be allowed to decrease to maintain that speed.
This should be done with reference to the horizon.
When the speed has stabilized, the airplane should
be retrimmed for “hands off” flight.
When the approximate gliding pitch attitude is
established, the airspeed indicator should be
checked. If the airspeed is higher than the recommended
speed, the pitch attitude is too low, and if
the airspeed is less than recommended, the pitch
attitude is too high; therefore, the pitch attitude
should be readjusted accordingly referencing the
horizon. After the adjustment has been made, the
airplane should be retrimmed so that it will maintain
this attitude without the need to hold pressure on the
elevator control. The principles of attitude flying
require that the proper flight attitude be established
using outside visual references first, then using the
flight instruments as a secondary check. It is a good
practice to always retrim the airplane after each
pitch adjustment.
A stabilized power-off descent at the best glide speed
is often referred to as a normal glide. The flight
instructor should demonstrate a normal glide, and
direct the student pilot to memorize the airplane’s
angle and speed by visually checking the airplane’s
attitude with reference to the horizon, and noting the
pitch of the sound made by the air passing over the
structure, the pressure on the controls, and the feel of
Increasing Lift-to-Drag Ratio
Increasing Angle of Attack
L/Dmax
Figure 3-17. L/DMAX.
Best Glide Speed
Too Fast
Too Slow
Figure 3-18. Best glide speed provides the greatest forward distance for a given loss of altitude.
Ch 03.qxd 7/13/04 11:08 AM Page 3-17
3-18
the airplane. Due to lack of experience, the beginning
student may be unable to recognize slight variations
of speed and angle of bank immediately by vision or
by the pressure required on the controls. Hearing will
probably be the indicator that will be the most easily
used at first. The instructor should, therefore, be certain
that the student understands that an increase in
the pitch of sound denotes increasing speed, while a
decrease in pitch denotes less speed. When such an
indication is received, the student should consciously
apply the other two means of perception so as to
establish the proper relationship. The student pilot
must use all three elements consciously until they
become habits, and must be alert when attention is
diverted from the attitude of the airplane and be
responsive to any warning given by a variation in the
feel of the airplane or controls, or by a change in the
pitch of the sound.
After a good comprehension of the normal glide is
attained, the student pilot should be instructed in the differences
in the results of normal and “abnormal” glides.
Abnormal glides being those conducted at speeds other
than the normal best glide speed. Pilots who do not
acquire an understanding and appreciation of these
differences will experience difficulties with accuracy
landings, which are comparatively simple if the
fundamentals of the glide are thoroughly understood.
Too fast a glide during the approach for landing
invariably results in floating over the ground for
varying distances, or even overshooting, while too
slow a glide causes undershooting, flat approaches,
and hard touchdowns. A pilot without the ability to
recognize a normal glide will not be able to judge
where the airplane will go, or can be made to go, in
an emergency. Whereas, in a normal glide, the flightpath
may be sighted to the spot on the ground on
which the airplane will land. This cannot be done in
any abnormal glide.
GLIDING TURNS—The action of the control
system is somewhat different in a glide than with
power, making gliding maneuvers stand in a class by
themselves and require the perfection of a technique
different from that required for ordinary power
maneuvers. The control difference is caused mainly by
two factors—the absence of the usual slipstream, and
the difference or relative effectiveness of the various
control surfaces at various speeds and particularly at
reduced speed. The latter factor has its effect
exaggerated by the first, and makes the task of
coordination even more difficult for the inexperienced
pilot. These principles should be thoroughly explained
in order that the student may be alert to the necessary
differences in coordination.
After a feel for the airplane and control touch have
been developed, the necessary compensation will be
automatic; but while any mechanical tendency exists,
the student will have difficulty executing gliding turns,
particularly when making a practical application of
them in attempting accuracy landings.
Three elements in gliding turns which tend to force the
nose down and increase glide speed are:
• Decrease in effective lift due to the direction of
the lifting force being at an angle to the pull of
gravity.
• The use of the rudder acting as it does in the entry
to a power turn.
• The normal stability and inherent characteristics
of the airplane to nose down with the power off.
These three factors make it necessary to use more back
pressure on the elevator than is required for a straight
glide or a power turn and, therefore, have a greater
effect on the relationship of control coordination.
When recovery is being made from a gliding turn, the
force on the elevator control which was applied during
the turn must be decreased or the nose will come up
too high and considerable speed will be lost. This error
will require considerable attention and conscious control
adjustment before the normal glide can again be
resumed.
In order to maintain the most efficient or normal glide
in a turn, more altitude must be sacrificed than in a
straight glide since this is the only way speed can be
maintained without power. Turning in a glide
decreases the performance of the airplane to an even
greater extent than a normal turn with power.
Still another factor is the difference in rudder action in
turns with and without power. In power turns it is
required that the desired recovery point be anticipated in
the use of controls and that considerably more pressure
than usual be exerted on the rudder. In the recovery from
a gliding turn, the same rudder action takes place but
without as much pressure being necessary. The actual
displacement of the rudder is approximately the same,
but it seems to be less in a glide because the resistance to
pressure is so much less due to the absence of the propeller
slipstream. This often results in a much greater
application of rudder through a greater range than is realized,
resulting in an abrupt stoppage of the turn when the
rudder is applied for recovery. This factor is particularly
important during landing practice since the student
almost invariably recovers from the last turn too soon
and may enter a cross-control condition trying to correct
the landing with the rudder alone. This results in landing
from a skid that is too easily mistaken for drift.
Ch 03.qxd 7/13/04 11:08 AM Page 3-18
3-19
There is another danger in excessive rudder use during
gliding turns. As the airplane skids, the bank will
increase. This often alarms the beginning pilot when it
occurs close to the ground, and the pilot may respond
by applying aileron pressure toward the outside of the
turn to stop the bank. At the same time, the rudder
forces the nose down and the pilot may apply back-elevator
pressure to hold it up. If allowed to progress, this
situation may result in a fully developed cross-control
condition. A stall in this situation will almost certainly
result in a spin.
The level-off from a glide must be started before
reaching the desired altitude because of the airplane’s
downward inertia. The amount of lead depends on the
rate of descent and the pilot’s control technique. With
too little lead, there will be a tendency to descend
below the selected altitude. For example, assuming a
500-foot per minute rate of descent, the altitude must
be led by 100 – 150 feet to level off at an airspeed
higher than the glide speed. At the lead point, power
should be increased to the appropriate level flight
cruise setting so the desired airspeed will be attained
at the desired altitude. The nose tends to rise as both
airspeed and downwash on the tail section increase.
The pilot must be prepared for this and smoothly control
the pitch attitude to attain level flight attitude so
that the level-off is completed at the desired altitude.
Particular attention should be paid to the action of the
airplane’s nose when recovering (and entering) gliding
turns. The nose must not be allowed to describe an arc
with relation to the horizon, and particularly it must
not be allowed to come up during recovery from turns,
which require a constant variation of the relative pressures
on the different controls.
Common errors in the performance of descents and
descending turns are:
• Failure to adequately clear the area.
• Inadequate back-elevator control during glide
entry resulting in too steep a glide.
• Failure to slow the airplane to approximate glide
speed prior to lowering pitch attitude.
• Attempting to establish/maintain a normal glide
solely by reference to flight instruments.
• Inability to sense changes in airspeed through
sound and feel.
• Inability to stabilize the glide (chasing the airspeed
indicator).
• Attempting to “stretch” the glide by applying
back-elevator pressure.
• Skidding or slipping during gliding turns due to
inadequate appreciation of the difference in rudder
action as opposed to turns with power.
• Failure to lower pitch attitude during gliding turn
entry resulting in a decrease in airspeed.
• Excessive rudder pressure during recovery from
gliding turns.
• Inadequate pitch control during recovery from
straight glides.
• “Ground shyness”—resulting in cross-controlling
during gliding turns near the ground.
• Failure to maintain constant bank angle during
gliding turns.
PITCH AND POWER
No discussion of climbs and descents would be
complete without touching on the question of what
controls altitude and what controls airspeed. The
pilot must understand the effects of both power and
elevator control, working together, during different
conditions of flight. The closest one can come to a
formula for determining airspeed/altitude control
that is valid under all circumstances is a basic principle
of attitude flying which states:
“At any pitch attitude, the amount of power used
will determine whether the airplane will climb,
descend, or remain level at that attitude.”
Through a wide range of nose-low attitudes, a descent
is the only possible condition of flight. The addition of
power at these attitudes will only result in a greater rate
of descent at a faster airspeed.
Through a range of attitudes from very slightly
nose-low to about 30° nose-up, a typical light airplane
can be made to climb, descend, or maintain
altitude depending on the power used. In about the
lower third of this range, the airplane will descend
at idle power without stalling. As pitch attitude is
increased, however, engine power will be required
to prevent a stall. Even more power will be required
to maintain altitude, and even more for a climb. At a
pitch attitude approaching 30° nose-up, all available
power will provide only enough thrust to maintain
altitude. A slight increase in the steepness of climb
or a slight decrease in power will produce a descent.
From that point, the least inducement will result in a
stall.
Ch 03.qxd 7/13/04 11:08 AM Page 3-19
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