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execution of 180° power-off approaches, the airplane
is flown on a downwind heading parallel to the landing
runway. The altitude from which this type of approach
should be started will vary with the type of airplane,
but it should usually not exceed 1,000 feet above the
ground, except with large airplanes. Greater accuracy
in judgment and maneuvering is required at higher
altitudes.
When abreast of or opposite the desired landing spot,
the throttle should be closed and altitude maintained
while decelerating to the manufacturer’s recommended
glide speed, or 1.4 VSO. The point at which the throttle
is closed is the downwind key position.
The turn from the downwind leg to the base leg should
be a uniform turn with a medium or slightly steeper
bank. The degree of bank and amount of this initial
turn will depend upon the glide angle of the airplane
and the velocity of the wind. Again, the base leg should
be positioned as needed for the altitude, or wind condition.
Position the base leg to conserve or dissipate
altitude so as to reach the desired landing spot.
The turn onto the base leg should be made at an altitude
high enough and close enough to permit the
airplane to glide to what would normally be the
base key position in a 90° power-off approach.
Although the key position is important, it must not be
overemphasized nor considered as a fixed point on
the ground. Many inexperienced pilots may gain a
conception of it as a particular landmark, such as a
tree, crossroad, or other visual reference, to be
reached at a certain altitude. This will result in a
mechanical conception and leave the pilot at a total
Figure 8-27. 180° power-off approach.
Medium or
Steeper Bank
Lower Partial Flaps
Maintain 1.4 Vs0
Lower Full Flaps
(as Needed)
Establish 1.3 Vs0
Key Position
Close Throttle
Normal Glide Speed
90°
Downwind Leg
Key Position
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loss any time such objects are not present. Both altitude
and geographical location should be varied as
much as is practical to eliminate any such conception.
After reaching the base key position, the approach and
landing are the same as in the 90° power-off approach.
360° POWER-OFF APPROACH
The 360° power-off approach is one in which the airplane
glides through a 360° change of direction to
the preselected landing spot. The entire pattern is
designed to be circular, but the turn may be shallowed,
steepened, or discontinued at any point to adjust the
accuracy of the flightpath.
The 360° approach is started from a position over the
approach end of the landing runway or slightly to the
side of it, with the airplane headed in the proposed
landing direction and the landing gear and flaps
retracted. [Figure 8-28]
It is usually initiated from approximately 2,000 feet or
more above the ground—where the wind may vary significantly
from that at lower altitudes. This must be
taken into account when maneuvering the airplane to a
point from which a 90° or 180° power-off approach
can be completed.
After the throttle is closed over the intended point of
landing, the proper glide speed should immediately be
established, and a medium-banked turn made in the
desired direction so as to arrive at the downwind key
position opposite the intended landing spot. At or just
beyond the downwind key position, the landing gear
may be extended if the airplane is equipped with
retractable gear. The altitude at the downwind key
position should be approximately 1,000 to 1,200 feet
above the ground.
After reaching that point, the turn should be continued
to arrive at a base-leg key position, at an altitude of
about 800 feet above the terrain. Flaps may be used at
this position, as necessary, but full flaps should not be
used until established on the final approach.
The angle of bank can be varied as needed throughout
the pattern to correct for wind conditions and to align
the airplane with the final approach. The turn-to-final
should be completed at a minimum altitude of 300 feet
above the terrain.
Common errors in the performance of power-off accuracy
approaches are:
• Downwind leg too far from the runway/landing
area.
• Overextension of downwind leg resulting from
tailwind.
• Inadequate compensation for wind drift on base
leg.
• Skidding turns in an effort to increase gliding
distance.
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