曝光臺 注意防騙 網曝天貓店富美金盛家居專營店坑蒙拐騙欺詐消費者

rather than risk a hazardous situation.
Final Approach
After the base-to-final approach turn is completed, the
aircraft should be aligned directly in the extension of the
centerline of the runway. The objective of a good fi nal
approach is to approach the runway with suffi cient energy
(manufacturer’s recommended airspeed) to land at or
beyond some predetermined point. The landing area should
provide suffi cient runway behind for variations in approach
conditions and runway ahead to allow either a full stop or a
go-around if needed.
If there is a crosswind of any kind, the aircraft should be
pointed into the wind slightly (see the Crosswind Approaches
and Landings section). Focus should be to keep the ground
track aligned with the centerline of the runway or landing
surface, so that drift (if any) is recognized immediately. On
a normal approach, with no crosswind drift, the longitudinal
axis should be kept aligned with the runway centerline
throughout the approach and landing.
After aligning the aircraft with the runway centerline, speed
is adjusted as required for the desired rate of descent. Slight
increases in power, if lower than expected, may be necessary
to maintain the descent angle at the desired approach
airspeed.
The descent angle should be controlled throughout the
approach so that the aircraft lands in the center of the runway
at the aiming point, as discussed earlier. The descent angle is
affected by all four fundamental forces that act on an aircraft
(lift, drag, thrust, and weight). If all the forces are constant,
the descent angle is constant in calm air. The pilot can control
these forces by adjusting the airspeed and power. The fi nal
approach sequence is shown in Figures 11-4 through 11-8.
In a descent for fi nal approach, if the WSC is slowed with
an angle of attack that is too high and without an increase
of power, the aircraft settles very rapidly and touches down
short of the desired area. For this reason, the pilot should
never try to stretch a glide by applying forward control bar
pressure alone to reach the desired landing area. Because this
brings the speed below the minimum drag speed, the gliding
distance decreases if power is not added simultaneously.
11-5
Figure 11-6. Coming to the runway and increasing speed slightly
within 50 feet of the ground.
Figure 11-7. Maintaining speed and position over the middle of
the runway.
Figure 11-8. Starting the roundout by increasing angle of attack
(AOA) slightly at about 10 to 15 feet above the runway.
Additionally, this is a lower energy approach and may be
slower than the manufacturer’s safe approach speed. The
proper angle of descent to the runway must be maintained at
the minimum speed recommended by the manufacturer, with
a fl atter descent angle obtained with increases in power as
required. Steeper descent angles are obtained with headwinds
or the pilot increasing speed/decreasing the angle of attack,
both of which are covered later in this chapter.
Estimating Height and Movement
During the fi nal approach, roundout, and touchdown, vision is
of prime importance. To provide a wide scope of vision and
to foster good judgment of height and movement, the pilot’s
head should assume a natural, straight-ahead position. The
pilot’s visual focus should not be fi xed on any one side or
any one spot ahead of the aircraft. The pilot should maintain
a deliberate awareness of the runway centerline (if available)
or distance from either side of the runway within his or her
peripheral fi eld of vision.
Accurate estimation of distance is, besides being a matter of
practice, dependent upon how clearly objects are seen; vision
must be focused properly so that important objects stand out
as clearly as possible. Speed blurs objects at close range. For
example, one can note this effect in an automobile moving
at high speed. Nearby objects seem to merge together in a
blur, while objects farther away stand out clearly. The driver
subconsciously focuses the eyes suffi ciently far ahead of the
automobile to see objects distinctly.
The distance at which the pilot’s vision is focused should be
proportionate to the speed at which the aircraft is traveling
over the ground. Thus, as speed is reduced during the
roundout, the focus distance ahead of the aircraft should be
decreased accordingly.
If the pilot attempts to focus on a reference that is too close
or looks directly down, the reference is blurred, and the
reaction is either too abrupt or too late. In this case, the
pilot’s tendency is to overcontrol, round out high, and make a
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：Weight-Shift Control Aircraft Flying Handbook(115)