BOMBARDIER Challenger 601-3A CL-600-2B16 Pilot Training Manual page 436

ATT Mode
If the NAV mode fails, the ATT mode pro-
vides a reversionary mode option that recov-
ers attitude and heading information. The ATT
mode operates during flight and on the ground.
Pulling the mode select switch away from the
MSU panel and rotating it to ATT selects the
mode.
In the ATT mode, the IRU stops providing po-
sition, velocity, and magnetic variation outputs.
The attitude and heading outputs are not as
accurate as the attitude and heading outputs
provided while in the navigation mode. When
selected, magnetic heading must be entered
via the ISDU or the FMS CDU and must be up-
dated periodically. Once ATT has been se-
lected, the NAV mode cannot be recovered.
Honeywell
ALIGN
OFF
Figure 16-22. Mode Select Unit ATT and Test Modes
16-24 CL 601-3A/R
ON BATT ANNUNCIATOR
COMES ON TO INDICATE THAT
THE IRS IS RECEIVING POWER
FROM THE IRS BACKUP BATTERY.
LASEREF
NAV
ATT
ON BATT
BATT FAIL ANNUNCIATOR
COMES ON TO INDICATE THAT
THE IRS BACKUP BATTERY IS
SUPPLYING LESS THAN THE
MINIMUM VOLTAGE REQUIRED
FOR IRS OPERATION.
CENTER PEDESTAL
FOR TRAINING PURPOSES ONLY
FlightSafety Canada
CL-600-2B16 PILOT TRAINING MANUAL
To select ATT, the mode select knob
must be pulled away from the MSU
front panel and then rotated clock-
wise.
Test Mode
Pressing the MSU TEST switch starts a 24
second internal IRS self-test that provides
three sets of test values. The test mode oper-
ates in the ALGN or NAV mode without af-
fecting basic IRS functions. Groundspeed
greater than 20 knots or mode select switch in
the ATT position prevents test mode operation.
FAULT ANNUNCIATOR
COMES ON TO INDICATE THAT
THERE IS A FAULT IN THE IRS.
NO AIR ANNUNCIATOR
COMES ON TO INDICATE
A COOLING FAILURE.
FAULT
NO AIR
BATT FAIL
TEST PUSHBUTTON
INDICATES A TEST SEQUENCE IN
WHICH THE IRS OUTPUTS THREE
SETS OF SPECIFIED TEST VALUES
SEQUENTIALLY. USED FOR MAIN-
TENANCE PURPOSES.
NOTE
TEST
L t é e
L t d .