TM 1-1510-225-10
3A-115
18. "Localizer" at 1.3 to 1.5 dots either
side of center beam. Will be repeated
three times at 4-second intervals.
19. "Glideslope" at 1.3 to 1.5 dots above
or below center of beam. Will be
repeated three times at 4-second
intervals.
20. "Altitude,
Altitude"
at
excessive
deviation from altitude selected on the
altitude alerter.
21. "Check Trim" when trim failure has
occurred. Will be repeated three
times at 4-second intervals.
22. "Autopilot"
when
autopilot
has
disconnected.
b. Normal Operation.
(1) Turn-on Procedure. The GPAAS is
operable when the following conditions have been
met.
1. BATT switch - ON.
2. AVIONICS MASTER PWR switch -
ON.
3. GPAAS POWER circuit breaker – Set.
4. RADIO ALTM circuit breaker – Set.
5. VA
FAIL
annunciator
light
–
Extinguished.
(2) GPAAS Ground Check.
1. GPAAS voice advisory VOL control –
Full clockwise.
2. VOICE
OFF
switch-indicator
–
Extinguished.
3. Audio control panel – Set listening
audio level.
4. VA
FAIL
annunciator
light
–
Extinguished.
5. DH set knob – Set decision height to
200 feet on EADI.
6. RALT
TEST
switch
–
Press.
"Minimum,
Minimum"
will
be
annunciated once followed by the
illumination of the VA FAIL light.
c. GPAAS Modes of Operation. The GPAAS
operates in the following modes of operation:
(1) Aural
"Two
Thousand”
Advisory
(Mode 1). The aural advisory "Two Thousand"
indicates that the aircraft is at a radio altitude of 2000
feet above ground level. This advisory is canceled
when valid information from the radio altimeter is lost,
during climb, or whenever the aircraft is out of the
operating altitude range of the radio altimeter.
(2) Hundred Foot Increment Aural Altitude
Advisories (Mode 2). The aural advisories "One
Thousand, Nine Hundred, Eight Hundred, Seven
Hundred, Six Hundred, Four Hundred, Three Hundred,
Two Hundred, One Hundred" indicate that the aircraft
is at the associated radio altitude in feet above ground
level. This advisory is canceled when valid information
from the radio altimeter is lost, during climb, or
whenever the aircraft is out of the operating altitude
range of the radio altimeter.
(3) Aural "Localizer” Advisory (Mode 3). The
aural advisory "localizer" indicates that the aircraft has
deviated from the center of the localizer beam in
excess of 1.3 to 1.5 dots. The localizer advisory is
armed when a valid localizer signal is detected and the
aircraft is below 1000 feet above ground level. It will
be repeated no more than three times at 4-second
intervals unless the aircraft is returned to less than 1.3
to 1.5 dots from the center of the localizer course. The
localizer advisory is disabled when a valid localizer
signal has been lost, during climb, below the decision
height set on the radio altimeter, or if the navigation
receiver is not tuned to a localizer frequency.
(4) Aural “Check Gear” Advisory (Mode 4).
The aural advisory “Check Gear” indicates that the
aircraft has descended to 500 feet AGL and the
landing gear is not down. This advisory is repeated
once at 100-foot intervals down to 100 feet AGL.
(5) Aural “Glideslope” Advisory (Mode 5).
The aural advisory “Glideslope” indicates that the
aircraft has exceeded 1.3 to 1.5 dots above or below
the center of the glideslope beam. The glideslope
advisory is armed when a valid glideslope signal is
detected and the aircraft is below 1,000 feet AGL. It
will be repeated no more than three times at 4-second
intervals unless the aircraft is returned to less than 1.3
to 1.5 dots from the center of the beam. The
glideslope advisory is disabled upon loss of a valid
glideslope signal, during climb, on a localizer back
course, below the decision height set on the radio
altimeter or, if the navigation receiver is not \turned to
