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This will cause lift to decrease again, and it must be
controlled by raising the nose and further increasing the
angle of attack. During the roundout, the airspeed is
being decreased to touchdown speed while the lift is
being controlled so the airplane will settle gently onto
the landing surface. The roundout should be executed
at a rate that the proper landing attitude and the proper
touchdown airspeed are attained simultaneously just as
the wheels contact the landing surface.
The rate at which the roundout is executed depends on
the airplane’s height above the ground, the rate of
descent, and the pitch attitude. A roundout started
excessively high must be executed more slowly than
one from a lower height to allow the airplane to
descend to the ground while the proper landing attitude
is being established. The rate of rounding out must also
be proportionate to the rate of closure with the ground.
When the airplane appears to be descending very
slowly, the increase in pitch attitude must be made at a
correspondingly slow rate.
Visual cues are important in flaring at the proper altitude
and maintaining the wheels a few inches above
the runway until eventual touchdown. Flare cues are
primarily dependent on the angle at which the pilot’s
central vision intersects the ground (or runway) ahead
and slightly to the side. Proper depth perception is a
factor in a successful flare, but the visual cues used
most are those related to changes in runway or terrain
perspective and to changes in the size of familiar
objects near the landing area such as fences, bushes,
trees, hangars, and even sod or runway texture. The
pilot should direct central vision at a shallow downward
angle of from 10° to 15° toward the runway as
the roundout/flare is initiated. [Figure 8-7]
Maintaining the same viewing angle causes the point
Increase
Angle of
Attack
Increase
Angle of
Attack
Increase
Angle of
Attack
78 Knots
70 Knots
65 Knots
60 Knots
10° to 15°
Figure 8-7.To obtain necessary visual cues, the pilot should look toward the runway at a shallow angle.
Figure 8-6. Changing angle of attack during roundout.
Ch 08.qxd 5/7/04 8:08 AM Page 8-5
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of visual interception with the runway to move
progressively rearward toward the pilot as the airplane
loses altitude. This is an important visual cue in
assessing the rate of altitude loss. Conversely, forward
movement of the visual interception point will indicate
an increase in altitude, and would mean that the pitch
angle was increased too rapidly, resulting in an over
flare. Location of the visual interception point in
conjunction with assessment of flow velocity of nearby
off-runway terrain, as well as the similarity of
appearance of height above the runway ahead of the
airplane (in comparison to the way it looked when the
airplane was taxied prior to takeoff) is also used to
judge when the wheels are just a few inches above
the runway.
The pitch attitude of the airplane in a full-flap approach
is considerably lower than in a no-flap approach. To
attain the proper landing attitude before touching
down, the nose must travel through a greater pitch
change when flaps are fully extended. Since the roundout
is usually started at approximately the same height
above the ground regardless of the degree of flaps
used, the pitch attitude must be increased at a faster
rate when full flaps are used; however, the roundout
should still be executed at a rate proportionate to the
airplane’s downward motion.
Once the actual process of rounding out is started, the
elevator control should not be pushed forward. If too
much back-elevator pressure has been exerted, this
pressure should be either slightly relaxed or held
constant, depending on the degree of the error. In some
cases, it may be necessary to advance the throttle
slightly to prevent an excessive rate of sink, or a stall, all
of which would result in a hard, drop-in type landing.
It is recommended that the student pilot form the habit
of keeping one hand on the throttle throughout the
approach and landing, should a sudden and unexpected
hazardous situation require an immediate application
of power.
TOUCHDOWN
The touchdown is the gentle settling of the airplane
onto the landing surface. The roundout and touchdown
should be made with the engine idling, and the airplane
at minimum controllable airspeed, so that the airplane
will touch down on the main gear at approximately
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AIRPLANE FLYING HANDBOOK 飞机飞行手册上(81)
