Learjet 60 - Page 164

Learjet 60
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Pilot's Manual
GROUND PROXIMITY
WARNING SYSTEM (GPWS) WITH WIND-
SHEAR DETECTION (OPTIONAL)
The Ground Proximity Warning
System with Windshear Detection
(GPWS/WS) provides the pilot with
aural and visual warning of po-
tentially dangerous flight paths relative to ground
and windshear
conditions .
The system automatically
and continuously monitors the airplane's
flight path with respect to terrain when
the aircraft is below 2450 feet
radio altitude (altitude AGL) . If the airplane's
projected flight path
would imminently
result in terrain impact, the system
issues appro-
priate visual
and voice warnings . Warnings are
issued for excessive
sink rate, excessive terrain closure rate, descent
after takeoff or missed
approach, proximity to terrain with
flaps and/or gear up, descent be-
low glideslope, and descent below decision
height (DH) .
The system computes
windshear and alerts the crew
of windshear of
sufficient magnitude to
be hazardous to the aircraft
. Windshear alerts
are given for
increasing headwind /decreasing
tailwind and/or up-
draft . Windshear warnings are
given for decreasing headwind/
increasing
tailwind and/or down-draft .
Issuance of a GPWS/WS warning
(red PULL UP or red
WNDSHR)
will trigger the Master WARN lights
to flash . Issuance of
a GPWS/
WS
alert (amber GPWS FAIL,
amber WIND SHEAR
FAIL, amber BE-
LOW G/S, or amber WNDSHR)
will trigger the
Master CAUT lights
to flash .
The system consists
of the GPWS/WS
computer, a set of
annunciator
light/switches on
the instrument
panel at each crew
position, a flap
override
switch, and associated
aircraft wiring . Voice
warnings are
made
through the cockpit
speakers and the headphones
. Voice
warn-
ings generated by the
GPWS will have priority
over voice warnings
generated by the TCAS (if
installed) . The system
receives inputs
from
either air data computer,
either AHRS, both
stall warning
vanes, ra-
dio altimeter, both nav
receivers, nose gear
down and locked
switch,
and the left flap 8°, 20°,
and 40° switch .
The system operates
on 115
VAC supplied
through the 1-amp
GPWS circuit breaker
and 28 VDC
supplied through
the 1-amp GPWS circuit
breaker on the
pilot's cir-
cuit breaker panel .
Refer to
the applicable AFM
supplement for further
details and oper-
ating
instructions .
PM-123
Change 3
5- 2 2A