STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS
detected, the digits are replaced with dashes the same color as the primary selected course. If the
data is missing, the data and dashes are removed from the display.
Display Select Panel
Two DSPs are located on the pedestal. The DSP controls consist of:
Radio altitude test switch/DH set knob
EHSI range select/format knob
Nav data button
Second course button
Weather radar button
Course control button
Radio Altitude Test Switch/DH Set Knob
The radio altitude test switch/DH set knob is a two-part knob that contains the radio altitude test
switch and a DH set knob. The DH knob, changes the selected DH value shown on the
respective EADI when rotated. Clockwise rotation increases the DH.
Navigation Data Button
The nav data button placarded NAV DTA, changes the nav data displayed on the EHSI.
Sequentially pressing the button selects TTG, GSP or RVEL/arrow displays, and relative wind
speed/arrow displays respectively.
The course knob is a three-part knob that consists of the active course source knob, the course
select knob, and the course direct-to switch.
1. Active Course Source Knob - The active course source knob, placarded CRS, is the outer
portion of knob. Rotate the knob to select the nav sensor that supplies active course information
displayed on the EHSI. The available selections are OFF, VOR/LOC, FMS, TCN, and