Specifications

SECTION III
MODEL 560 INSTRUMENTATION AND AVIONICS
The area at the lower part of the scale (0.57 to 0.1) represents the normal operating range of the
airplane, except for approach and landing. The narrow white arc (0.57 to 0.63) covers the approach and
landing range and the middle of the white arc, 0.6, represents the optimum landing approach (V
APP
or
V
REF
). The yellow range (0.63 to 0.85) represents a caution area where the airplane is approaching a
critical angle-of-attack. The red arc (0.85 to 1.0) is a warning zone that represents the beginning of low
speed buffet followed by full stall. If the angle-of-attack system loses power or becomes inoperative for
other reasons, the needle will deflect to the top of the scale and stow at a 1.0 indication. A red X will also
appear at the EADI slow/fast indication. The airplane may not be flown if the stick shaker is found to be
inopertive on the preflight check, or if the angle-of-attack system is otherwise inoperative.
WARNING
IF THE ANGLE-OF-ATTACK VANE HEATER FAILS AND THE
VANE BECOMES ICED, THE STICK SHAKER MAY NOT
OPERATE OR MAY ACTIVATE AT NORMAL APPROACH
SPEEDS
An optional approach indexer, mounted on the pilot’s glareshield, provides a “heads up” display of
deviation from the approach reference. The display is in the form of three red lighted symbols which are
used to indicate the airplane angle-of-attack. High angle-of-attack is analogous to low airspeed; low
angle-of-attack is analogous to high airspeed. Illumination of the symbols is progressive as the airplane
angle-of-attack changes. When the airplane speed is on reference the center circle will be illuminated. As
the speed decreases from reference (.6) the circle illumination will dim and the top chevron illumination will
increase until the top chevron is fully illuminated and the circle is extinguished. As the angle-of-attack
becomes high the top chevron will begin to flash.
When the airplane is accelerating from the on-speed reference the illumination of the circle will dim
and illumination of the bottom chevron will increase until the circle is extinguished and only the bottom
chevron is illuminated. The top chevron points down, indicating that the angle-of-attack must be decreased
to eliminate the deviation. The bottom chevron points up to indicate that the angle-of-attack must be
increased to eliminate the deviation. The indexer is active any time the nose gear is down and locked and
the airplane is not on the ground. There is a twenty second delay after takeoff before the indexer will
activate.
Figure 3-7. Angle-of-Attack Indicator And Indexer
I 56OMB-01 Configuration AA 3-15