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approach should be governed by three factors:
1. Wind direction and velocity
2. Dimensions and slope of the chosen fi eld
3. Obstacles in the fi nal approach path and the fi eld
itself
These three factors are seldom compatible. When compromises
must be made, the pilot should aim for a wind/obstacle/terrain
combination that permits a fi nal approach with some margin
for error in judgment or technique. A pilot who overestimates
the gliding range may be tempted to stretch the glide
13-7
Figure 13-5. Using treetops to “hang” the wing during an
emergency landing.
across obstacles in the approach path. For this reason, it is
sometimes better to plan the approach over an unobstructed
area regardless of wind direction. Experience shows that a
collision with obstacles at the end of a ground roll, or slide,
is much less hazardous than striking an obstacle at fl ying
speed before the touchdown point is reached.
Terrain Types
Since an emergency landing on suitable terrain resembles
a situation with which the pilot should be familiar through
training, only the more unusual situation is discussed.
Confi ned Areas
The natural preference to set the aircraft down on the ground
should not lead to the selection of an open spot between trees
or obstacles where the ground cannot be reached. Once the
intended touchdown point is reached, and the remaining open
and unobstructed space is very limited, it may be better to
force the aircraft down on the ground than to delay touchdown
until it stalls (settles). An aircraft decelerates faster after it is
on the ground than while airborne.
A river or creek can be an inviting alternative in otherwise
rugged terrain. The pilot should ensure that the water or creek
bed can be reached without snagging the wings. The same
concept applies to road landings with one additional reason
for caution: manmade obstacles on either side of a road may
not be visible until the fi nal portion of the approach.
When planning the approach across a road, it should be
remembered that most highways and even rural dirt roads
are paralleled by power or telephone lines. Only a sharp
lookout for the supporting structures or poles may provide
timely warning.
If the only possible landing alternative is a small clearing and
it is not possible to land the WSC aircraft, the BPS should
be deployed, if equipped, as discussed earlier.
Trees
Although a tree landing is not an attractive prospect, the
following general guidelines help to make the experience
survivable.
For example, if the trees are taller than 15 feet and not dense
enough to assure the wing could be set on top of them, use the
BPS if so equipped. This provides two possible chances of
hanging up in the trees and a slower descent rate if the WSC
aircraft does not become lodged in the trees and continues a
descent to the ground.
If the trees are estimated to be shorter than 15 feet or a BPS is
not installed on the WSC aircraft, landing in the trees should
be performed as follows:
• Keep the groundspeed low by heading into the
wind.
• Make contact at minimum indicated airspeed, but not
below stall speed, and “hang” the wing in the tree
branches in a nose-high landing attitude. Involving
the underside of the fuselage and both wings in the
initial tree contact provides a more even and positive
cushioning effect. Hold the control bar with both hands
more than shoulder width apart and bend elbows to
lessen the impact of the control bar against the chest.
[Figure 13-5]
• Avoid direct contact of the fuselage with heavy tree
trunks.
• Try to land in low, closely spaced trees with wide,
dense crowns (branches) close to the ground, which
are much better than tall trees with thin tops; the latter
allow too much free fall height. (A free fall from 75
feet results in an impact speed of about 40 knots or
about 4,000 fpm.)
• Ideally, initial tree contact should be symmetrical;
that is, both wings should meet equal resistance in the
tree branches. This distribution of the load helps to
13-8
maintain proper aircraft attitude. It may also preclude
the loss of one wing, which invariably leads to a more
rapid and less predictable descent to the ground.
• If heavy tree trunk contact is unavoidable once the
aircraft is on the ground, it is best to involve both
wings simultaneously by directing the aircraft between
two properly spaced trees. However, do not attempt
this maneuver while still airborne.
Water Landings ( Ditching)
　
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本文鏈接地址：Weight-Shift Control Aircraft Flying Handbook(147)