After aligning the airplane with the runway centerline,
the final flap setting should be completed and the pitch
attitude adjusted as required for the desired rate of
descent. Slight adjustments in pitch and power may
be necessary to maintain the descent attitude and the
desired approach airspeed.
The descent angle should be controlled throughout the
approach so that the airplane will land in the center
of the first third of the runway. The descent angle is
affected by all four fundamental forces that act on an
airplane (lift, drag, thrust, and weight). If all the
forces are constant, the descent angle will be constant
in a no-wind condition. The pilot can control these
forces by adjusting the airspeed, attitude, power, and
drag (flaps or forward slip). The wind also plays a
prominent part in the gliding distance over the
ground [Figure 8-2]; naturally, the pilot does not have
control over the wind but may correct for its effect
on the airplane’s descent by appropriate pitch and
power adjustments.
The descent angle should be controlled throughout the
approach so that the airplane will land in the center
of the first third of the runway. The descent angle is
affected by all four fundamental forces that act on an
airplane (lift, drag, thrust, and weight). If all the
forces are constant, the descent angle will be constant
in a no-wind condition. The pilot can control these
forces by adjusting the airspeed, attitude, power, and
drag (flaps or forward slip). The wind also plays a
prominent part in the gliding distance over the
ground [Figure 8-2]; naturally, the pilot does not have
control over the wind but may correct for its effect
on the airplane’s descent by appropriate pitch and
power adjustments.
Considering the factors that affect the descent angle on
the final approach, for all practical purposes at a given
pitch attitude there is only one power setting for one
airspeed, one flap setting, and one wind condition.
A change in any one of these variables will require
an appropriate coordinated change in the other controllable
variables. For example, if the pitch attitude
is raised too high without an increase of power, the
airplane will settle very rapidly and touch down
short of the desired spot. For this reason, the pilot
should never try to stretch a glide by applying backelevator
pressure alone to reach the desired landing
spot. This will shorten the gliding distance if power is
not added simultaneously. The proper angle of descent
and airspeed should be maintained by coordinating
pitch attitude changes and power changes.
The objective of a good final approach is to descend at
an angle and airspeed that will permit the airplane to
reach the desired touchdown point at an airspeed
which will result in minimum floating just before
touchdown; in essence, a semi-stalled condition. To
accomplish this, it is essential that both the descent
angle and the airspeed be accurately controlled. Since
on a normal approach the power setting is not fixed as
in a power-off approach, the power and pitch attitude
should be adjusted simultaneously as necessary, to
control the airspeed, and the descent angle, or to attain
the desired altitudes along the approach path. By lowering
the nose and reducing power to keep approach
airspeed constant, a descent at a higher rate can be
made to correct for being too high in the approach.
This is one reason for performing approaches with partial
power; if the approach is too high, merely lower
the nose and reduce the power. When the approach is
too low, add power and raise the nose.
