SKY899
Installation Manual
009-11900-001
Installation - Page 2-23
Revision F
July 18, 2013
2.7.4
Squat Switch (Weight-On-Wheels)
This input is to be connected to the squat switch (weight-on-wheels) to sense when the aircraft is on the
ground.
NOTE
If the aircraft is not equipped with a squat switch, it is recommended that
a squat switch or an alternate switch be installed.
Squat switch connection:
SQUAT
P1-24
If a squat switch is not available, this input could be tied to an airspeed switch inline with the pitot system
as an alternate input for the squat switch. In this configuration care should be taken to ensure the switch is
set to trigger at a speed consistent with take-off and landing.
If it is not possible to install a squat switch or airspeed switch, ground this input and select "Active Low
when configuring "Weight on Wheels" in the service menu. With this configuration the pilot must toggle
the system in and out of standby manually. Traffic will only be displayed when the pilot switches out of
the standby position.
With a squat switch installed, SKYWATCH HP will automatically switch out of standby 8 to 10 seconds
after takeoff and switch back to standby 24 seconds after landing. A squat switch would also prevent the
pilot from placing SKYWATCH HP in standby (i.e., pressing the
STB button) while the aircraft is in-
flight.
2.8 ALTERNATE DISPLAY
Alternate display(s) are connected to the ARINC-429 TX1 output channel. Each alternate display will
show the information consistent with the capabilities of that particular display. Display functions can be
controlled through the discrete soft-key inputs or the alternate display depending on the display's
capabilities. Refer to paragraph 2.9.3 for alternate display connection information and paragraph 2.20 for
soft-key connections. Alternate display driver configurations are covered in Chapter 4.
2.9 ARINC-429
The ARINC-429 interface can be divided into four sections: general sensor inputs, mode S transponder
input/output, alternate display output and future input/output options. The TRC has seven receive
channels and three transmit channels that are used to accomplish the various interfaces. However, two
receiver and two transmitter channels are not used at this time (future option). ARINC-429 labels
accepted and transmitted are listed in tables A-2 and A-3.
The document reference is online, please check the correspondence between the online documentation and the printed version.