曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
some lift may continue to be generated by the wing.
After touchdown, the nosewheel should be lowered to
the runway to maintain directional control. During
deceleration, the nose may be pitched down by braking
and the weight transferred to the nosewheel from the
main wheels. This does not aid in braking action, so
back pressure should be applied to the controls without
lifting the nosewheel off the runway. This will enable
the pilot to maintain directional control while keeping
weight on the main wheels.
Careful application of the brakes can be initiated after
the nosewheel 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 can be stopped by releasing
the brake pressure. Also, braking effectiveness is not
enhanced by alternately applying and reapplying brake
pressure. The brakes should be 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 should be used to keep the wings level in much
the same way they were used in flight. If a wing starts
to rise, aileron control should be applied toward that
wing to lower it. The amount required will depend on
speed because as the forward speed of the airplane
decreases, the ailerons will 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
may be gradually relaxed to place normal weight on
the nosewheel to aid in better steering. If available
runway permits, the speed of the airplane should be
allowed to dissipate in a normal manner. Once the
airplane has slowed sufficiently and has turned on to
the taxiway and stopped, the pilot should retract the
flaps and clean up the airplane. 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, should be formed from
the very beginning of flight training and continued in all
future flying activities.
STABILIZED APPROACH CONCEPT
A stabilized approach is one in which the pilot establishes
and maintains a constant angle glidepath
Ch 08.qxd 5/7/04 8:08 AM Page 8-7
PDF Create! 5 Trial
www.nuance.com
8-8
towards a predetermined point on the landing runway.
It is based on the pilot’s judgment of certain visual
clues, and depends on the maintenance of a constant
final descent airspeed and configuration.
An airplane descending on final approach at a constant
rate and airspeed will be traveling in a straight line
toward a spot on the ground ahead. This spot will not
be the spot on which the airplane will touch down,
because some float will inevitably occur during the
roundout (flare). [Figure 8-9] Neither will it be the spot
toward which the airplane’s nose is pointed, because
the airplane is flying at a fairly high angle of attack,
and the component of lift exerted parallel to the Earth’s
surface by the wings tends to carry the airplane forward
horizontally.
The point toward which the airplane is progressing is
termed the “aiming point.” [Figure 8-9] It is the point
on the ground at which, if the airplane maintains a
constant glidepath, and was not flared for landing, it
would strike the ground. To a pilot moving straight
ahead toward an object, it appears to be stationary. It
does not “move.” This is how the aiming point can be
distinguished—it does not move. However, objects in
front of and beyond the aiming point do appear to move
as the distance is closed, and they appear to move in
opposite directions. During instruction in landings, one
of the most important skills a student pilot must acquire
is how to use visual cues to accurately determine the
true aiming point from any distance out on final
approach. From this, the pilot will not only be able to
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：
AIRPLANE FLYING HANDBOOK 飞机飞行手册上(83)
