In addition, the configuration of the power indicators installed
in each aircraft may vary to include tile following types of
power indicators: tachometers, manifold pressure indicator,
engine pressure ratio indicator, fuel flow gauges, etc.

The control instruments do not indicate how fast the aircraft
is flying or at what altitude it is flying. In order to determine
these variables and others, a pilot needs to refer to the
performance instruments.

Performance Instruments
The performance instruments directly reflect the performance
the aircraft is achieving. The speed of the aircraft can be
referenced on the airspeed indicator. The altitude can be
referenced on the altimeter. The aircraft's climb performance
can be determined by referencing the vertical speed indicator
(VSI). [Figure 4-26] Other performance instruments
available are the heading indicator, angle of attack indicator,
and the slip/skid indicator.

The performance instruments will most directly reflect a
change in acceleration, which is defined as change in velocity
or direction. Therefore, these instruments indicate if the
aircraft is changing airspeed, altitude, or heading, which are
horizontal, vertical, or lateral vectors.

Navigation instruments
The navigation instruments are comprised of global
positioning system (GPS) displays and indicators, very high
frequency omnidirectional range/nondirectional radio beacon
(VOR/NDB) indicators, moving map displays, localizer, and
glide slope (GS) indicators. [Figure 4-27] The instruments
indicate the position of the aircraft relative to a selected
navigation facility or fix. Navigation instruments allow
the pilot to maneuver the aircraft along a predetermined
path of ground-based or spaced-based navigation signals
without reference to any external visual cues. The navigation
instruments can support both lateral and visual inputs.