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The landing process must
never be considered complete until the airplane decelerates
to the normal taxi speed during the landing roll or
has been brought to a complete stop when clear of the
landing area. Numerous accidents occur as a result of
pilots abandoning their vigilance and failing to maintain
positive control after getting the airplane on the ground.
A pilot must be alert for directional control difficulties
immediately upon and after touchdown due to the ground
friction on the wheels. Loss of directional control
may lead to an aggravated, uncontrolled, tight turn
on the ground, or a ground loop. The combination of
centrifugal force acting on the center of gravity (CG)
and ground friction of the main wheels resisting it
during the ground loop may cause the airplane to tip
or lean enough for the outside wingtip to contact the
ground. This imposes a sideward force that could collapse
the landing gear.
The rudder serves the same purpose on the ground as
it does in the air—it controls the yawing of the
airplane. The effectiveness of the rudder is dependent
on the airflow, which depends on the speed of the airplane.
As the speed decreases and the nose wheel has been lowered
to the ground, the steerable nose provides more positive
directional control.
The brakes of an airplane serve the same primary purpose
as the brakes of an automobile—to reduce speed
on the ground. In airplanes, they are also used as an
aid in directional control when more positive control
is required than could be obtained with rudder or nose
wheel steering alone.
To use brakes, on an airplane equipped with toe brakes,
the pilot slides the toes or feet up from the rudder
pedals to the brake pedals. If rudder pressure is being
held at the time braking action is needed, that pressure
is not to be released as the feet or toes are being
slid up to the brake pedals because control may be lost
before brakes can be applied.
Putting maximum weight on the wheels after touchdown
is an important factor in obtaining optimum braking
performance. During the early part of rollout, some
lift continues to be generated by the wing. After touchdown,
the nose wheel is lowered to the runway to maintain
directional control. During deceleration, the nose may
pitch down by braking and the weight transferred to
the nose wheel from the main wheels. This does not aid
in braking action, so back pressure is applied to the
controls without lifting the nose wheel off the runway.
This enables directional control while keeping weight
on the main wheels.
Careful application of the brakes is initiated after
the nose wheel is on the ground and directional control
is established. Maximum brake effectiveness is just
short of the point where skidding occurs. If the brakes
are applied so hard that skidding takes place, braking
becomes ineffective. Skidding is stopped by releasing
the brake pressure. Braking effectiveness is not enhanced
by alternately applying, releasing, and reapplying brake
pressure. The brakes are applied firmly and smoothly
as necessary.
During the ground roll, the airplane’s direction
of movement can be changed by carefully applying pressure
on one brake or uneven pressures on each brake in the
desired direction. Caution must be exercised when applying
brakes to
avoid overcontrolling.
The ailerons serve the same purpose on the ground as
they do in the air—they change the lift and drag
components of the wings. During the after-landing roll,
they are used to keep the wings level in much the same
way they are used in flight. If a wing starts to rise,
aileron control is applied toward that wing to lower
it. The amount required depends on speed because as
the forward speed of the airplane decreases, the ailerons
become less effective. Procedures for using ailerons
in crosswind conditions are explained further in this
chapter, in the Crosswind Approach and Landing section.
After the airplane is on the ground, back-elevator pressure
is gradually relaxed to place weight on the nose wheel
to aid in better steering. If available runway permits,
the speed of the airplane is allowed to dissipate in
a normal manner. Once the airplane has slowed sufficiently
and has turned on to the taxiway and stopped, retract
the flaps and perform the after-landing checklist. Many
accidents have occurred as a result of the pilot unintentionally
operating the landing gear control and retracting the
gear instead of the flap control when the airplane was
still rolling. The habit of positively identifying both
of these controls, before actuating them, must be formed
from the very beginning of flight training and continued
in all future flying activities.
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