a localizer frequency. This advisory is inhibited by the
weight on wheels strut switch.
(Mode 6). The aural advisory Minimum, Minimum
indicates that the aircraft is at the radio altitude
selected by the crew with the radio altimeter DH set
knob located, on the EFIS control panel. This advisory
is canceled when valid information from the radio
altimeter is lost, during climb, whenever the aircraft is
above 1,000 feet AGL, or whenever the aircraft is out
of the operating altitude range of the radio altimeter.
(Mode 7). The aural advisory Altitude, Altitude
indicates the approach to a pre-selected altitude as the
aircraft reaches a point 1,000 feet from the selected
altitude or, after reaching the selected altitude, when
the aircraft deviates more than 250 feet from the
(8) Aural Check Trim, Check Trim, Check
Trim Advisory. The aural advisory Check Trim,
Check Trim, Check Trim indicates that the autopilot
has had a trim failure.
(9) Aural Autopilot Advisory. The aural
advisory Autopilot indicates that the autopilot has
d. Emergency Procedures. If an emergency
or malfunction makes it necessary to disable the
GPAAS, pull the GPAAS POWER circuit breaker,
located on the right sidewall circuit breaker panel,
Figure 2-6. GPAAS audio may be turned off by
pressing the VOICE OFF switch.
3A-34. TRANSPONDER (APX-100).
information on the APX-100 Transponder.
3A-35. TRANSPONDER (MST 67A).
a. Description. The transponder (MST 67A)
responds to interrogation to allow the aircraft to be
located in range and azimuth by a ground Air Traffic
Control Radar Beacon System radar site. Upon
receiving mode A or mode C interrogation the
transponder transmits coded returns that identify the
aircraft by code number and/or reports the altitude at
which the aircraft is operating. This mode S
transponder transmits random replies called squitter
which include the unique mode S address assigned to
the transponder at installation. The ATC mode S
ground station receives this mode S reply and can
selectively interrogate one specific address. The
transponder receives on a frequency of 1030
megahertz and transmits coded reply pulses on a
frequency of 1090 megahertz. The range of the
transponder is line of sight. The transponder (MST
67A) is powered through a 3-ampere circuit breaker,
placarded XPNDR NO. 2, located on the right sidewall
circuit breaker panel, Figure 2-6.
Controls (MST 67A). Refer to Figure 3A-69.
(1) Reply Indicator. The reply indicator is an
R annunciator located in the upper left portion of the
display. The reply indicator illuminates to indicate that
the transponder is replying to ground interrogation. An
interrogation that causes the R annunciator to
illuminate will normally be processed with each sweep
of the search radar that will normally be a 10 to
15 second interval.
(2) Ident Code/Flight Level Test Display.
automatically controls display brightness.
(4) Ident Switch. The ident switch, placarded
IDT, when pressed momentarily then released, holds
the ident reply for approximately 25 seconds to assure
the proper reply within at least one radar sweep.
During this time, the IDT annunciator will be
illuminated on the transponder control unit display.
The ident function may also be activated from switches
mounted on each control wheel, placarded ATC
(5) Ident Indicator. The ident indicator,
placarded IDT, illuminates when the ident function has
been activated by pressing the IDT switch on the
transponder control panel or one of the control wheel
ident switches placarded ATC IDENT.
(6) Function Switch. The function switch,
placarded TST / SBY / ON / ALT / VFR, is used to
select the operating mode of the transponder.
(a) TST. The test (TST) position of the
function switch provides for a preflight or airborne
check of transponder operation. This check is
independent of any ground interrogation. Setting the
function switch to TST should cause the reply (R)
annunciator to flash and the flight level (FL)
annunciator to illuminate. The transponder transmitter
is inhibited during the test function. After 3 seconds,
the unit will revert to the altitude (ALT) reporting mode.