Slip/Skid indicator
The slip/skid indicator is the small portion of the lower
segmented triangle displayed on the attitude indicator. This
instrument depicts whether the aircraft's longitudinal axis is
aligned with the relative wind, [Figure 5-54]

The pilot must always remember to cross-check the roll index
to the roll pointer when attempting to maintain straight flight.
Any time the heading remains constant and the roll pointer and
the roll index are not aligned, the aircraft is in uncoordinated
flight. To make a correction, the pilot should apply rudder
pressure to bring the aircraft back to coordinated flight.

Power Control
Power produces thrust which, with the appropriate angle of
attack of the wing, overcomes the forces of gravity, drag,
and inertia to determine airplane performance.

Power control must he related to its effect on altitude and
airspeed, since any change in power setting results in a change
in the airspeed or the altitude of the airplane. At any given
airspeed, the power setting determines whether the airplane
is in level flight, in a climb, or in a descent. If the power is
increased in straight-and-level flight and the airspeed held
constant, the airplane will climb; if power is decreased while
the airspeed is held constant, the airplane will descend. On
the other hand, if altitude is held constant, the power applied
will determine the airspeed.

The relationship between altitude and airspeed determines the
need for a change in pitch or power. If the airspeed is off the
desired value always check the altimeter before deciding that
a power change is necessary. Think of altitude and airspeed
as interchangeable; altitude can be traded for airspeed by
lowering the nose, or convert airspeed to altitude by raising
the nose. If altitude is higher than desired and airspeed is
low, or vice versa, a change in pitch alone may return the
airplane to the desired attitude and airspeed. [Figure 5-55] If
both airspeed and altitude are high or if both are low, then a
change in both pitch and power is necessary in order to return
to the desired airspeed and altitude. [Figure 5-56]

For changes in airspeed in straight-and-level flight, pitch, bank,
and power must he coordinated in order to maintain constant
altitude and heading. When power is changed to vary airspeed
in straight-and-level flight, a single-engine, propeller-driven
airplane tends to change attitude around all axes of movement.

Therefore, to maintain constant altitude and heading, apply
various control pressures in proportion to the change in power.
When power is added to increase airspeed, the pitch instruments
indicate a climb unless forward-elevator control pressure is
applied as the airspeed changes. With an increase in power the

airplane tends to yaw and roll to the left unless counteracting
aileron and rudder pressures are applied. Keeping ahead of
these changes requires increasing cross-check speed, which
varies with the type of airplane and its torque characteristics,
the extent of power and speed change involved.

Power Settings
Power control and airspeed changes are much easier when
approximate power settings necessary to maintain various
airspeeds in straight-and-level flight are known in advance.
However, to change airspeed by any appreciable amount, the
common procedure is to underpower or overpower on initial
power changes to accelerate the rate of airspeed change. (For
small speed changes, or in airplanes that decelerate or accelerate
rapidly, overpowering or underpowering is not necessary.)

Figure 5-55. An aircraft decreasing in airspeed while gaining
altitude. In this case, the pilot has decreased pitch.

Figure 5-56. Figure shows both an increase in speed and altitude
where pitch adjustment alone is insufficient. In this situation, a
reduction of power is also necessary.